Ian MacCallum
Founder · Parra
Ian MacCallum is the founder of Tax Days, the tax-residency tracker that combines US state, US federal, and international day-count rules in one app. He built Tax Days after watching travellers, snowbirds, and remote workers try to track residency thresholds on paper calendars and spreadsheets, and lose audits because of it.
Every rule in Tax Days is researched and maintained from primary sources: IRS publications and the Internal Revenue Code, individual state revenue-department guidance and statutes, HMRC's Statutory Residence Test guidance, and the relevant double-tax treaties. Where the law is contested, the guides cite the governing case (for example, Matter of Gaied for New York's permanent-place-of-abode standard) rather than paraphrasing it.
Tax Days and these guides are general information, not tax or legal advice. Ian is not a CPA, enrolled agent, or attorney, anyone making a real residency decision should confirm it with a qualified tax professional. The aim here is to explain the rules accurately, link to the source, and give you a defensible day-by-day record.
Guides by Ian (124)
- Guides
Defending a residency audit: timeline, evidence, and what auditors actually do
State residency audits target high-earners who claim to have left. Here's what to expect, the timeline, the evidence requests, and how to defend your domicile and day count.
- Federal
Form 8840 and the closer-connection exception
Even if you meet the IRS Substantial Presence Test, you can avoid US tax-resident status by claiming closer connection on Form 8840, but only if you meet specific day-count and residency conditions.
- Federal
The SPT 3-year weighted formula, with worked examples
The IRS Substantial Presence Test uses a 3-year weighted day-count formula. Here it is in plain math, with multiple worked examples for visa types and travel patterns.
- Guides
Tax Days vs. Topia: a comparison for individual cross-border residents
Topia is enterprise mobility software for global employers. Tax Days is for individuals. Here's why the comparison matters and which is right for you.
- Guides
The remote worker's multi-state tax guide: nexus, day counts, and double tax
Working remotely from multiple states triggers state nexus, withholding obligations, and potential double taxation. Here's how to track days, manage employer obligations, and avoid surprise tax bills.
- Guides
Tax Days vs. Domicile365: feature, price, and privacy comparison
Domicile365 is a long-running residency-tracking service for snowbirds and cross-border workers. Tax Days is the iPhone-native alternative. Here's how they compare.
- US States
Pennsylvania residency rules: domicile, statutory residence, and Philly's local tax
Pennsylvania has a 3.07% flat tax, but Philadelphia adds a 3.75% city wage tax. Here's how PA's domicile test, statutory residence rule, and local tax interact for departing residents.
- Guides
Tax Days vs. iReside: which residency tracker is right for you?
iReside and Tax Days both target privacy-conscious, internationally-mobile users. Here's an honest comparison on price, tracking method, jurisdictions, and privacy.
- US States
Illinois residency rules: domicile, the abode test, and Chicago tax exposure
Illinois taxes residents at a flat 4.95%. Combined with Chicago's lifestyle tax exposure, the move to Florida is popular among Chicago-area professionals. Here's how Illinois residency really works.
- Guides
The expat day counter guide: residency, treaties, and the rules you'll actually face
If you're an American living abroad, a Brit in the EU, or anyone with a foreign tax home, day counts decide where you owe tax. Here's the playbook for tracking residency thresholds and treaty tie-breakers.
- Guides
Tax Days vs. TaxBird: which residency tracker is right for you?
TaxBird and Tax Days both target snowbirds and cross-border residents. Here's an honest comparison on price, jurisdictions, GPS, privacy, and audit support.
- Guides
Tax Days vs. Monaeo: an honest comparison
Monaeo is a long-running residency tracker for high-net-worth individuals at $1,200+/year. Tax Days is a privacy-first iPhone app at $19.99/year. Here's how they compare on jurisdictions, accuracy, and what each does best.
- US States
West Virginia's 183-Day Rule & the 30-Day Exit: Residency Both Ways
West Virginia's 183 day rule catches non-domiciliaries with a home in-state, while leavers can only break residency through a strict 30-day domicile safe harbor.
- Guides
How Snowbirds Should Track Tax Days: US States and the US-Canada Border
Snowbirds cross two very different borders for tax: the US state line and the US-Canada border. How to count days for each, the forms that protect you, and the app that keeps the record.
- US States
Oklahoma's Seven-Month Residency Rule: Months, Not 183 Days
Oklahoma generally presumes you're a resident if you spend more than seven months of the year in-state. The statute is written in months, not 183 days, and the presumption is rebuttable.
- US States
North Dakota's 7-Month (210-Day) Residency Rule: A High Bar for Snowbirds
North Dakota's residency test taxes you as a resident if you keep a permanent home there and spend more than seven months (210 days) in-state, a higher bar than the usual 183 days.
- US States
New Mexico's 185-Day Rule: Why Only Full 24-Hour Days Count
New Mexico taxes you as a resident if you're physically present 185 days or more, but only full 24-hour days count. Partial arrival and departure days generally don't.
- US States
Nebraska's 183-Day Residency Rule: Permanent Abode & Any-Part-of-a-Day Counting
Nebraska taxes you as a resident if you keep a permanent place of abode there and spend more than 183 days in-state, and any part of a day generally counts as a full day.
- US States
Kentucky's 183-Day Rule & Reciprocity: A Cross-Border Commuter's Guide
Kentucky generally treats you as a resident at over 183 days with a home in-state, but reciprocity with seven neighbors keeps cross-border wages taxed only at home.
- US States
Iowa's 183-Day Rule: A Rebuttable Presumption You Can Fight
Iowa presumes you maintain a permanent place of abode there if you keep an Iowa home and pass 183 days in-state. It's rebuttable, but the burden shifts to you.
- US States
Indiana's 183-Day Residency Rule, Domicile & Reciprocity Explained
Indiana taxes you as a resident if you keep a permanent home and spend over 183 days in-state, or if you're domiciled there. Plus how reciprocity works for KY, MI, OH, PA, and WI commuters.
- US States
Hawaii's 200-Day Rule: The Rebuttable Presumption of Residency
Hawaii presumes you are a resident if you spend more than 200 days there in a tax year. It is a rebuttable presumption: how it works and how to overcome it.
- US States
Washington DC's 183-Day Residency Rule: The Abode-Maintained Trap
DC taxes you as a statutory resident if you maintain a place of abode in the District for 183 days or more, a count that can include temporary absences, not just physical presence.
- US States
Arkansas' Six-Month Residency Rule: Home Plus More Than Six Months
Arkansas treats you as a resident only if you keep a permanent home there and spend more than six months in-state. Both conditions are required, and the rule is months-based.
- US States
Alabama's Seven-Month Residency Rule: A Higher Bar Than 183 Days
Alabama presumes you're a resident if you spend more than seven months of the year in-state, whether or not consecutive, a higher bar than the usual 183 days.
- International
Germany's 183-day rule and 'center of vital interests' test
Germany determines tax residency by domicile (Wohnsitz), habitual abode (gewöhnlicher Aufenthalt), or the 183-day test under treaties. Here's how each works for expats and remote workers.
- Guides
Year-End Residency Review: A December Audit-Prep Checklist
A year end residency review locks in your day count and ties before the tax year closes. Use this December checklist to verify days, fix gaps, and prep early.
- Guides
Tax Residency for Yacht Crew & Pilots: Seafarers' Earnings & Day Counting
Yacht crew tax residency depends on the days you spend on land, not at sea or in the air. Here's how seafarer reliefs and day counting actually work for crew.
- Guides
Which Tax Residency Rules Apply to You? State + Visa + Test Matrix
This routing guide explains tax residency rules by situation, matching your country, US state, and visa to the exact test and guide that applies to your case.
- International
Vietnam Tax Residency for Expats: 183-Day Rule & Long-Stay Visas
Vietnam tax residency hinges on 183 days or a permanent home and taxes worldwide income. Here's how the day count, long-stay visas, and the no-DNV reality work.
- International
Turkey Expat Tax Residency: 183-Day Rule & Returning-Resident Deferral
Turkey tax residency turns on a six-month presence test and taxes residents on worldwide income. Here is how the 183-day rule and the deferral exception work.
- International
South Africa Tax Residency: 183-Day Test & Ordinary Residence
The South Africa 183 day rule is the physical-presence test. See how it and ordinary residence decide SARS tax residency on worldwide income, and how to exit.
- Guides
Schengen Overstay Penalties & Tax Implications
Schengen overstay penalties range from fines and entry bans to deportation. Here is what overstaying the 90/180 limit costs, plus the tax angle few expect.
- Guides
Perpetual Traveler Tax Status: Myth vs Reality
The perpetual traveler tax myth promises a life with no tax home. In reality you almost always keep a domicile somewhere, here is what actually decides it.
- International
Offshore Account Reporting by Residency Status (FBAR / CRS / FATCA)
Foreign account reporting residency drives it: US persons file FBAR and FATCA, CRS-country residents are auto-reported, non-doms and non-residents differ.
- International
Monaco Tax Residency: The Bank Deposit Path & French Exception
How Monaco tax residency works: the bank deposit requirement, no personal income tax, the 183-day presence rule, and the big French exception expats miss.
- Guides
Medical, Exempt & Military Days: Official Rules by Jurisdiction
The medical day exception tax residency rule, exempt-individual days, and military days each cut your taxable count under the IRS SPT, US states, and UK SRT.
- International
Ireland Non-Dom: Indefinite Remittance Basis & Treaty Interactions
The Ireland non dom regime has no deemed-domicile clock, so the remittance basis can last indefinitely. How it works, what it taxes, and how treaties interact.
- International
Greece Golden Visa & the 183-Day Tax-Residency Trigger
Greece golden visa tax, made clear: the permit grants residency rights, not tax residency. Greek worldwide tax usually triggers only past 183 days a year.
- International
Georgia (Country) Tax Residency: The 183-Day Rule & 1% Regime
Georgia country tax residency hinges on the 183-day rule, and its territorial system plus the low Individual Entrepreneur regime keep foreign income untaxed.
- International
Estonia e-Residency vs Tax Residency: What It Does (and Doesn't) Do
Estonia e-Residency is a digital business ID, not tax residency. What it changes for your company's tax, what it leaves untouched personally, and the traps.
- International
Brazil Tax Residency: 183-Day Test & 2025 Non-Resident Cert Changes
Brazil tax residency starts after more than 183 days in any rolling 12-month window. How the day count, RFB exit rules, and 2025 dividend changes work.
- International
Argentina Residency & Bienes Personales After the 2025 Reform
How Argentina tax residency works: the 12-month physical-presence rule, worldwide wealth tax, and how the 2025 Bienes Personales reform changed the rates.
- Guides
April Tax Deadline & Residency Audit Season: A Planning Guide
Residency audit season starts in April. Here's how to file a clean part-year or nonresident return and pre-build day-count evidence that survives an audit.
- International
Andorra Passive Residency & the 10% Flat-Tax Scheme
Andorra tax residency explained: how passive residency works, the upfront deposit and local investment, the flat 10% income tax, and no wealth or estate tax.
- US States
Massachusetts 183-day rule and the Millionaire's Tax: residency for high earners
Massachusetts taxes residents at 5%, plus a 4% Millionaire's Tax surcharge above $1M. Here's how the 183-day rule and 'place of abode' test work for departing residents.
- US States
Vermont Residency Guide & Neighboring-State Audit Coordination
Vermont tax residency explained: the domicile rule, the 183-day statutory test, and how to coordinate days when you split time across New England and New York.
- US States
Utah Residency: 183-Day Rule & Domicile Requirements
How Utah decides if you're a resident for tax: the 183-day rule, domicile tests, and what counts. A clear guide to Utah residency rules for filers and movers.
- International
The Permanent-Home Tie-Breaker: OECD Article 4(2) in Practice
When two countries both claim you, a tax treaty tie breaker permanent home test usually decides residence. Here is how OECD Article 4(2) works in practice.
- US States
South Carolina Part-Year Residency & Personal-Services Income
South Carolina residency rules for part-year movers: how the state taxes income before and after your move, what counts as SC-source pay, plus retiree tips.
- Guides
Schengen 90/180 with Multiple Passports: Can You Reset Your Count?
Schengen multiple passports do not reset your 90/180 day count. The limit follows the person, not the document. Here is how it works and what overstaying costs.
- US States
Rhode Island Residency Rules & New England Tax Implications
Rhode Island residency rules explained: the 183-day statutory test, domicile, part-year filing, and what happens when you split time across New England states.
- Guides
Tax Residency for Retirees: Social Security, Medicare IRMAA & Domicile
Retiree tax residency turns on domicile and day count: it sets how your Social Security, pension, and IRA withdrawals are taxed, and it shapes Medicare too.
- Guides
Tax residency audit defense: the evidence hierarchy and what precedent rewards
Residency audit defense is won on evidence, not arguments. Here's the evidence hierarchy auditors weight, contemporaneous over reconstructed, and why.
- Guides
New Year Tax Residency Planning: The 2026 Checklist for Snowbirds & Expats
A tax residency planning checklist for 2026: reset your day count, lock in your domicile, and stay under the thresholds that matter for snowbirds and expats.
- US States
Montana Residency: Big Sky Domicile Defense
Montana residency rules explained: how domicile and the statutory presence test decide who pays income tax, and how to defend a clean move in or out of state.
- US States
Missouri Residency Rules & Midwest Reciprocal Agreements
Missouri residency: domicile, the abode plus 183-day statutory trap, and why the state has no reciprocity deals with Kansas, Illinois, or any other neighbor.
- US States
Maine Residency Rules: Safe-Harbor Days & Lower Audit Pressure
Maine residency rules hinge on domicile plus a 183-day count and a safe-harbor for people abroad. Learn how the day test works and how to stay nonresident.
- US States
Louisiana Residency & the Domicile Act Mechanics
Louisiana residency turns primarily on civil-law domicile, with a six-month presence test as a backstop. Learn how the Civil Code defines, keeps, and lets you change a Louisiana domicile.
- Federal
Long-Term Resident & the 8-of-15-Year Rule: How 'Any Portion' Counts Years
The long term resident 8 of 15 years rule sets US exit tax exposure for green card holders, why any part of a tax year counts in full, and how to count yours.
- US States
Kansas Residency Rules & Great Plains Tax Comparison
Kansas residency rules explained: how the state uses domicile (plus a rebuttable six-month presumption) to tax income, and how Kansas compares to its Great Plains neighbors.
- US States
Idaho Residency Rules & Remote-Worker Multistate Strategy
Idaho residency rules turn on domicile plus a 270-day presence test. Here's how remote workers manage multistate nexus, day counts, and dual-state tax exposure.
- Federal
Green-Card Abandonment (Form I-407): Timing & Tax-Residency Implications
Form I-407 tax timing controls when your US residency ends and whether the exit tax applies. A clear guide to dating your green-card abandonment right.
- Guides
Dual Citizens & Treaty Tie-Breakers: When the US Saving Clause Overrides
Dual citizen tax residency: when two countries both claim you, a treaty tie-breaker picks one, but the US saving clause can override it. Here's how to tell.
- International
Departure Tax & Exit Strategies: Australia, Canada, US, Argentina
Departure tax leaving residency explained for Australia, Canada, the US and Argentina, deemed disposition rules, thresholds and timing moves that cut the bill.
- US States
Delaware 183-Day Rule & Corporate-Tie Connections
Delaware residency rules tax you as a resident if you're domiciled there, or keep a place of abode and spend more than 183 days in-state. Here's how it works.
- Guides
Tax Residency for Crypto Traders: Capital Gains by Jurisdiction & the 30% Trap
Crypto trader tax residency decides how your gains are taxed: a jurisdiction guide to capital gains, the US nonresident 30% trap, and exchange KYC day proof.
- US States
Connecticut residency audits: 183-day rule, abode test, and the Greenwich playbook
Connecticut audits high-earning residents who relocate to Florida or Texas with surprising aggression. Here's the 183-day statutory rule, abode test, and what auditors look for.
- US States
New Jersey residency rules: domicile, statutory residence, and the 183-day trap
New Jersey taxes residents at up to 10.75%. The state's residency rules mirror New York's but are sometimes audited even more aggressively. Here's how to defend your domicile claim.
- US States
Wisconsin 183-Day Rule & Reciprocal Agreements (IL, IN, KY, MI)
The Wisconsin 183 day rule taxes you as a resident if you keep an abode and spend 183+ days in-state. Reciprocity with IL, IN, KY, and MI changes how you file.
- Federal
The US Non-Resident Alien Capital-Gains Trap: 183 Days & the 30% Rate
Non resident alien capital gains 30% rule: spend 183+ days in the US in one tax year and you can owe a flat 30% tax on net US-source gains. Who it catches.
- Guides
Tax Residency Spreadsheet vs App: Why Google Sheets Won't Survive an Audit
A tax residency spreadsheet feels free and flexible, but it fails under audit. Here's an honest comparison of tracking days in Google Sheets vs a dedicated app.
- International
Residence-Based vs Territorial Tax Systems Explained
Residence-based systems tax your worldwide income, territorial ones tax only local-source income, and your day count is what decides which one applies to you.
- International
Portugal NHR (Grandfathered): Rules for Pre-2025 Applicants
Pre-2025 Portugal NHR holders keep full benefits despite the Portugal NHR replacement closing the regime. What stays, who qualifies, and how days protect it.
- International
Philippines Digital Nomad Visa: Tax on Foreign Income
Philippines digital nomad visa tax explained: the DNV lets you work remotely while the Philippines taxes non-citizens only on Philippine-source income.
- US States
Oregon's 200-Day Residency Rule: A Higher Bar & Snowbird Advantage
The Oregon 200 day rule taxes you as a resident if you keep a permanent home there and spend over 200 days in-state, a higher bar than the usual 183 days.
- International
New Zealand Tax Residency: 183-Day Rule & Ordinary Residence
New Zealand tax residency turns on a 183-day count and a permanent place of abode. Learn how the rules work, how to lose residency, and how Australia compares.
- US States
New Hampshire Residency: A No-Tax State After the I&D Repeal
New Hampshire tax residency in 2026: now a full no-tax state after the interest & dividends repeal. How to establish NH domicile and survive a departure audit.
- US States
Minnesota Residency Rules: Aggressive Auditor Profile & the 183-Day Test
A Minnesota residency audit targets departing high earners. Here's the 183-day statutory rule, the abode test, what counts as a Minnesota day, and how to win.
- International
Malta Non-Dom & the Remittance Basis: 183-Day Rule + Minimum Tax
Malta non dom tax residency taxes foreign income only when you remit it to Malta, not what you leave abroad. How the 183-day rule and minimum tax work here.
- Federal
J-1 Exchange Visitors: SEVIS Day-Counting & the Exempt-Year Window
How the j1 visa substantial presence test works: the exempt-year window (2-of-7 vs 5 calendar years), SEVIS tracking, and the early-departure restart trap.
- International
Italy's Non-Dom Substitute-Tax Regime
The Italy non dom regime lets new tax residents pay one flat annual substitute tax on all foreign income for up to 15 years. Here is how it works in 2026.
- International
Indonesia & Remote-Worker Tax: 183-Day Trigger & Territorial Rules
Indonesia B211A tax: the visa does not make you a resident. Being present 183+ days in any 12-month window does, flipping you to worldwide-income taxation.
- International
Golden Visa Is Not Tax Residency: The 183-Day Rule Still Applies
Golden visa tax residency is set by day-count rules, not a permit. Here is why the 183-day rule still decides where you pay tax and what actually changes it.
- Federal
FBAR & FATCA for Tax-Residency Planning: Reporting as a US Person
A green card or a passing Substantial Presence Test count makes you a US person who must report foreign accounts on the FBAR, and often Form 8938 under FATCA.
- Federal
Expatriation Exit Tax & Day-Counting: Form 8854 for Covered Expatriates
How the expatriation exit tax works under IRC 877A: the covered-expatriate tests, the 8-of-15-year green card rule, and why day-counting decides your fate.
- International
Costa Rica Tax Residency: Territorial System & 183-Day Rule
Costa Rica tax residency relies on a territorial system that leaves most foreign income untaxed. Here's how the 183-day rule and key residency visas work.
- US States
Colorado's 6-Month Rule & Snowbird Residency Strategy
Colorado residency rules make you a resident if you're domiciled there or keep a home and spend over six months in-state. How snowbirds plan around the line.
- International
Colombia Tax Residency for Digital Nomads: The DNV
Colombia tax residency triggers after more than 183 days in any rolling 365-day window, then Colombia taxes your worldwide income. How the DNV fits in.
- US States
Arizona's Remote-Worker Safe Harbor vs. the 183-Day Rule
Arizona remote worker tax explained: how the nonresident short-stay safe harbor relieves withholding for limited work days, and how it differs from residency.
- International
UAE and Dubai tax residency: 90 vs 183 days, and what you actually need
The UAE has 0% personal income tax, but qualifying as a tax resident takes more than landing in Dubai. Here are the 90-day and 183-day pathways and what other countries will demand to recognize your status.
- International
Spain's Beckham Law and 183-day rule: residency for inbound expats
Spain taxes residents at up to 47%, but the Beckham Law gives qualifying inbound workers a 24% flat rate for 6 years. Here's how the 183-day rule and Beckham Law interact.
- US States
Washington State Residency Rules: Capital Gains Tax & Domicile Defense
Washington state residency rules explained: no income tax, but a capital gains tax on high earners and your old state's audit risk when you move to WA.
- International
UK FIG Regime: The 4-Year Foreign Income & Gains Exemption (Post-Non-Dom)
The UK FIG regime gives new UK residents 4 tax-free years of foreign income and gains after non-dom rules ended in 2025. Here's how the day-counting works.
- International
Thailand DTV & Tax Residency: the 180-Day Rule, Day-Counting & Foreign Income
Thailand digital nomad tax turns on one number: a Thai DTV visa never makes you a tax resident, but 180+ days in a calendar year does. Here is how it works.
- International
Territorial Tax Countries 2026: The List & Residency Thresholds
Territorial tax countries tax only local-source income, leaving foreign earnings untaxed. Here's the 2026 list, the residency-day thresholds, and key caveats.
- US States
Tennessee Residency Guide: Zero Income Tax & Escaping High-Tax-State Audits
Tennessee has no state income tax since the Hall tax repeal. Learn how Tennessee tax residency works and how to survive your old state's departure audit.
- Guides
Tax Residency Edge Cases: Do Layovers, Partial Days & the Midnight Rule Count?
Whether a layover counts as day tax residency depends on the rule. New York counts any part of a day; the IRS and UK midnight rule are kinder. Full guide.
- International
Portugal IFICI (NHR 2.0): 20% Flat Tax for Qualified Professionals
Portugal IFICI tax (NHR 2.0), the post-2024 successor to NHR, gives qualifying science, tech, and R&D professionals a 20% flat tax once they become Portuguese tax residents.
- International
Panama Territorial Tax & Residency: the 183-Day Threshold and 0% on Foreign Income
Panama taxes only Panama-source income, foreign income is generally untaxed. How Panama tax residency, the 183-day rule, and visa vs. residency work in 2026.
- US States
Nevada Domicile & the 183-Day Rule: No Income Tax, Common Audit Paths
Nevada tax residency has no 183-day rule because the state levies no income tax, the real fight is abandoning California or New York. Here is how to win it.
- International
Malaysia DE Rantau & Tax Residency: The 182-Day Threshold for Tech Professionals
Malaysia DE Rantau tax residency hinges on days, not the visa: 182 days in a calendar year makes you a resident. Here's the threshold and foreign-income rule.
- International
India NRI Tax Residency: The 182-Day Rule & the 120-Day Change
The India 182 day rule NRI guide: stay under 182 days to keep non-resident status, but high earners turn resident at 120 days. Here is how it all works.
- Guides
How Many Days Can I Spend in a Country Before Becoming a Tax Resident?
Wondering how many days tax resident status takes? It's usually 183 days a year, but the US, UK, and US states count differently. Get the per-country answer.
- International
Hong Kong Tax Residency: The 180/300-Day Cumulative Trap
Hong Kong tax residency turns on a 60-day visit rule plus a 180-day or 300-day-over-two-years treaty day count. Here's how to track all three correctly.
- Federal
H-1B Holders & the Substantial Presence Test: Day-Counting for Skilled Workers
The H1B substantial presence test trips up skilled workers: H-1B days are not exempt. Learn how the IRS counts US days, transfers, and the dual-status year.
- Federal
Form 8840 Filing & Audit Defense: Proving Closer Connection to a Foreign Country
How to file the Form 8840 closer connection statement: the deadline, who carries the burden of proof, how the IRS scores your ties, and what wins an audit.
- Federal
First-Year Choice Election: Green-Card Arrivals & Dual-Status Filing
The first year choice green card question confuses many arrivals. Learn the 31-day, 75% presence test under IRC 7701(b)(4) and how dual-status filing works.
- Federal
F-1 to OPT to H-1B: Tax Residency Through the Transition
F1 OPT tax residency explained: the 5-year exempt window, when OPT days start counting toward the Substantial Presence Test, and the H-1B transition year.
- International
Day-Counting Variations by Country: Calendar, Tax-Year, Rolling & Cumulative
How countries count tax residency days varies: calendar-year, non-calendar tax-year, rolling 12-month, weighted, and cumulative methods, with worked examples.
- International
Cyprus Non-Dom: The 17-Year Regime & Deemed-Domicile Rules
Cyprus non dom tax residency offers up to 17 years of zero tax on dividends and interest. How the 60-day fast-track and deemed-domicile clock work in 2026.
- International
China's 183-Day Rule & the 6-Year Worldwide-Income Trap
The China 6 year rule taxes foreigners on worldwide income only after six straight years of 183+ days residence. One trip over 30 days abroad resets the clock.
- Guides
Best Tax Residency Tracker Apps 2026: Complete Comparison
An honest 2026 guide to the best tax residency tracker app: TaxBird, Domicile365, Monaeo, Topia, iReside, and Tax Days compared on price, coverage, GPS, and privacy.
- International
Portugal NHR and IFICI: residency days, eligibility, and how to track them
Portugal's NHR program closed to new applicants in 2024 but the successor IFICI regime offers similar benefits. Here's how 183 days, the habitual residence test, and ongoing-eligibility days work.
- Guides
The digital nomad tax guide: residency, Schengen, and the rules that catch you
Digital nomads face overlapping tax-residency rules from every country they visit. Here's the playbook for staying out of accidental tax residency while working from anywhere.
- US States
Texas residency for snowbirds: domicile, day counts, and what to track
Texas has no state income tax, making it a top destination for high-earners leaving California, New York, and Illinois. Here's how to establish Texas domicile and survive an old-state audit.
- International
The UK Statutory Residence Test (SRT) explained: ties, days, and automatic tests
The UK SRT is a complex three-stage test: automatic non-resident tests, automatic resident tests, then a sufficient-ties test. Here's how to count days, ties, and what triggers UK tax residency.
- US States
Florida domicile: the complete guide to changing your tax residency
Establishing Florida domicile cuts your state income tax to zero, but only if you do it correctly. Here's the documentation, day-count strategy, and audit-proofing your old state will scrutinize.
- US States
How California decides residency: the 9-month rule and facts test
California has no fixed day-count threshold for tax residency. Instead it uses a 9-month presumption plus a facts-and-circumstances test that's harder to defend than New York's 184-day rule.
- Federal
The Substantial Presence Test, calculated step-by-step
The IRS Substantial Presence Test (SPT) is a 3-year weighted formula that determines whether non-citizens are US tax residents. Here's the formula, exemptions, and how to calculate it correctly.
- US States
The snowbird tax tracker guide: NY ↔ FL, NJ ↔ FL, IL ↔ FL
If you split time between a high-tax state (NY, NJ, IL, CT) and a no-tax state (FL, TX, TN), one missed day can cost you tens of thousands in state income tax. Here's how snowbirds keep their domicile claim airtight.
- International
Schengen 90/180 explained: rolling windows, non-EU citizens, and how to count
The Schengen 90/180 rule is the most misunderstood tax and immigration rule in Europe. Here's how the rolling 180-day window works, with examples and a calculator-style worked example.
- US States
The New York 184-day rule: a survivor's guide
New York's 184-day + permanent place of abode rule is one of the most aggressively audited residency tests in the world. Here's how it works, what triggers an audit, and how to defend yourself.
- Guides
How the 183-day rule decides your tax residency
A plain-English guide to the 183-day rule used by most countries. How a 'day' is counted, what triggers tax residency, and where the rule has surprising twists.