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.
A year-end residency review is the December habit of verifying your day count and ties before the tax year closes, so that on December 31 your numbers are locked, documented, and defensible rather than something you reconstruct under audit pressure months later. The goal is simple: know exactly how many days you spent in each jurisdiction, confirm you're on the right side of every threshold that applies to you, and fix anything that's still fixable while there's still time on the clock.
Most residency mistakes aren't dramatic. They're a handful of uncounted days, a stale billing address, or a trip you forgot to log. December is when those small things are cheap to fix and January is when they aren't. This checklist walks through the review in the order that matters.
Why December is the deadline that matters
Almost every residency rule is measured against the calendar year. The 183-day rule, most state statutory-residency day counts, and the U.S. substantial presence test all close their books on December 31. Once the year ends, your day count is whatever your records say it is, and if your records are thin, the tax authority's reconstruction fills the gap. Their version rarely favors you.
December is also the last month you can still change the outcome. If you're three days from tipping into residency somewhere, a canceled trip in late December keeps you under the line. If you're trying to establish residency or domicile in a new place, the final weeks of the year are your last chance to add days, sign a declaration, or close out an old-state tie before the year is sealed.
Block 30 minutes in mid-December for this review, early enough that you can still cancel or add a trip if a threshold is close, late enough that the year is nearly complete.
Step 1: Reconcile your day count
Start with the number everything else hangs on. Pull your travel log for the year and reconcile it against independent sources, you're looking for trips you forgot to record and partial days you counted wrong.
- Cross-check against hard evidence: boarding passes, hotel and rental confirmations, calendar entries, and credit-card statements. Each should map to a day in your log.
- Confirm your partial-day rule. Most U.S. states count any part of a day of physical presence as a full day; the federal SPT does too. Travel days you treated as zero may actually count as one.
- Account for transit and layovers. Some jurisdictions exempt pure airport transit; others don't. Know which rule applies before you assume a layover is free.
- Flag exempt days. Medical-necessity days, certain treaty days, and exempt-individual days don't always count, but only if you can document why. Mark them now while the reason is fresh.
If you've been tracking with the 183-day calculator or a dedicated day-counting app, this step is a verification pass, not a reconstruction. If you've been keeping it in your head, this is where you build the contemporaneous record you'll wish you had if an audit ever lands.
Step 2: Check every threshold you're near
A day count only means something against a threshold. Map your numbers to each rule that touches your situation and note your margin. The ones that bite are the ones where you're within a week of the line.
| Threshold | Where it applies | What to verify in December |
|---|---|---|
| 183 days in-country | Most treaty and domestic rules | Days in each country; margin to 183 |
| State statutory residency | NY, NJ, CT, and similar states | Abode maintained + days at/over the state's limit (often 183 or 184) |
| Substantial presence test | U.S. federal (non-citizens) | Weighted 3-year count via the SPT formula |
| Schengen 90/180 | Schengen-area visitors | Rolling 90-in-180 window, not a calendar year |
| New-residency minimums | Where you're trying to qualify | Enough days/ties to claim the new jurisdiction |
Two of these don't follow the calendar and trip people up every December. The U.S. substantial presence test weights the current year plus the two prior years, so your December position depends on history, not just this year. And the Schengen 90/180 rule uses a rolling 180-day window, a New Year's trip to Europe is measured against the previous six months, not a fresh January count.
Being a few days under a foreign threshold doesn't automatically make you a non-resident. Domicile, a permanent home, and the center of your economic life can override a clean day count. The day number is necessary, not always sufficient.
Step 3: Review your ties and domicile
Day counts win statutory-residency disputes; ties win domicile disputes. If you changed your home base this year, or want your position to survive scrutiny, December is the time to confirm the paper trail matches the story you're telling.
- Severed old-state ties: driver's license surrendered, voter registration cancelled, old-jurisdiction memberships dropped, financial-account addresses updated.
- Established new ties: new license, voter registration, primary doctors and dentists, homestead or domicile declaration where available.
- Billing and mailing addresses: phone, brokerage, retirement, banking. A stale old-state address on a phone bill is the first thing an auditor pulls.
- Family location: where your spouse and minor children live carries heavy weight. If they stayed behind, your day count needs to be airtight.
- Where your stuff lives: the larger, more permanent home and the location of items "near and dear" (heirlooms, pets, key possessions) point to your real center of life.
If you moved to a low-tax state this year, also confirm any formal step that has a dated paper trail, for example a Florida Declaration of Domicile. Signing it in December still counts for this year; waiting until January does not.
Step 4: Fix what's still fixable
This is the step that justifies doing the review in December rather than April. If a threshold is uncomfortably close, you still have levers, but only for a few more weeks.
- One day from tipping over? Cancel, shorten, or relocate a late-December trip to stay under the line.
- Short on days where you want residency? Spend the final weeks of the year there to push past the minimum.
- Missing a dated tie? Sign the declaration, update the license, or change the billing address before January 1.
- Gaps in your log? Backfill them now from receipts and calendars while the year is fresh, not 18 months later from memory.
None of this is about gaming the rules. It's about making sure the documented reality matches where you actually were and what you actually did, so that a true position is also a provable one.
Step 5: Archive the year's record
Close the loop by saving a clean, dated copy of the year, a day-by-day log with locations, plus the supporting documents behind any exempt or disputed days. Residency audits often arrive a year or more after filing, and they can stretch on for years. The record you archive this December is the record that defends you then.
A purpose-built tracker makes this trivial: Tax Days keeps a contemporaneous log all year and exports a clean year-end summary you can hand to your accountant. Whatever tool you use, the principle is the same, finish the year with one authoritative file, not a folder of half-remembered trips.
Do this review every December and audit season stops being a scramble. Each year-end snapshot becomes a building block, and multi-year tests like the substantial presence test are already reconciled before you file.
Frequently asked questions
When should I do a year-end residency review?
Mid-December is ideal. The year is nearly complete, so your day count is essentially final, but you still have a couple of weeks to cancel or add a trip, sign a domicile declaration, or update an address if a threshold is close.
What does it mean to lock in your day count?
It means reconciling your travel log against hard evidence, boarding passes, hotel bookings, card statements, calendar entries, so that on December 31 you have one accurate, documented day count per jurisdiction rather than a number you'd have to reconstruct later from memory.
Does the Schengen 90/180 rule reset on January 1?
No. Schengen uses a rolling 180-day window, not a calendar year, so a New Year's trip to Europe is measured against the previous six months of stays. Check it with a Schengen calculator before you travel, see /tools/schengen-calculator.
If I'm a few days under 183, am I safe from being a tax resident?
Not necessarily. A day count under a threshold helps, but domicile, a permanent home, and the center of your economic and family life can make you a resident regardless. Day counting is necessary but not always sufficient.
What records should I keep from my year-end review?
A day-by-day log with locations for the full year, plus the documents behind any exempt or disputed days. Save one clean, dated file. Audits can arrive a year or more after filing, so the archive you create in December is what defends you later.
Can changes I make in December still count for this tax year?
Yes. Trips taken, declarations signed, and addresses changed before December 31 count toward the current year. Waiting until January pushes them into next year, which is exactly why the review belongs in December.