Tax Days vs. Daysium
Daysium and Tax Days solve the same problem, proving where you were on which day, but they are priced for different people. Daysium is a membership product aimed at high-net-worth individuals and the family offices and trustees who advise them, starting at £950/year for a single jurisdiction. Tax Days is a $29.99/year iPhone app that covers all 200+ jurisdictions at once. Here is the head-to-head. (Daysium pricing below is its published rate as of August 2026, confirm the current figure on daysium.com before buying.)
Pricing at a glance
Privacy-first iPhone app. No accounts, no servers. Optional iCloud sync via Apple's encrypted CloudKit.
UK-built tax residency and day-counting platform for high-net-worth individuals and their advisers, combining automatic GPS logging, geo-tagged photo evidence, and a concierge service, sold on annual memberships that start in the four figures.
Feature comparison
| Feature | Tax Days | Daysium |
|---|---|---|
| Annual cost | $29.99/year, all rules included | £950 (Professional) to £5,000+ (Platinum/Enterprise) |
| Jurisdictions included | All 200+, no tier limits | 1 on Professional, 3 on Private Client, unlimited on Platinum |
| Free tier | Yes (limited rules) | No, membership only |
| Tracking method | Automatic background tracking (Pro) or manual entry | Automatic GPS logging |
| Location tracking optional | Yes, you can log trips entirely by hand | GPS logging is the core of the product |
| Data location | On your iPhone + optional iCloud | Daysium's platform |
| Evidence capture | Contemporaneous day log, exportable | Day log plus geo-tagged photo evidence |
| Human concierge | No, self-serve | Yes, on Private Client and above |
| Adviser / family-office portal | No | Yes, on Platinum and Enterprise |
| US state rules | All 50, with state-specific tests | Configurable rules, not a packaged 50-state set |
| Schengen 90/180 | Yes | Configurable as a jurisdiction rule |
| UK SRT | Yes | Yes, UK is its home market |
| Platform | iPhone (iOS 26+), Mac via Catalyst | iPhone, iPad, Mac (M1+), web portal on higher tiers |
Which one is right for you?
Tax Days is best for…
- Anyone who wants every jurisdiction included instead of paying per tier.
- People who want the option to track without handing over continuous GPS.
- Individuals without an adviser, family office, or trustee in the loop.
- Anyone for whom £950/year is out of proportion to the tax at stake.
Daysium is best for…
- High-net-worth individuals who want a concierge to review the record with them.
- Family offices and trustees managing several people from one portal.
- Anyone who wants geo-tagged photo evidence attached to the day log.
- Users who need SSO, data-residency options, or a formal enterprise contract.
Bottom line: Daysium is a premium, advised service and prices accordingly: £950/year buys one jurisdiction, and covering three costs £2,500. Tax Days covers every jurisdiction for $29.99/year and keeps the data on your phone. If you want a human reviewing your position and a portal your trustee can log into, Daysium is built for that. If you want the day count itself, correct and defensible, Tax Days does the same job for a fraction of the price.
Frequently asked questions
Is Daysium or Tax Days better?
It depends on whether you are buying software or a service. Tax Days is a $29.99/year iPhone app that runs the day count for every jurisdiction and keeps your data on-device. Daysium is a membership starting at £950/year that adds geo-tagged photo evidence, a concierge service on higher tiers, and an adviser portal for family offices. For the day count alone, Tax Days is far cheaper and covers more jurisdictions out of the box.
How much does Daysium cost?
As of August 2026 Daysium publishes four tiers: Professional at £950/year (one user, one tax jurisdiction), Private Client at £2,500/year (up to three jurisdictions plus concierge service), Platinum at £5,000/year (three user licences, unlimited jurisdictions, adviser access), and Enterprise at custom pricing from £5,000/year. Check daysium.com/pricing for the current figures.
Daysium vs Domicile365: which should I pick?
They sit at opposite ends of the market. Domicile365 is a consumer-priced app aimed mainly at US state residency and snowbirds. Daysium is a four-figure UK membership aimed at high-net-worth individuals and their advisers, with concierge support and a family-office portal. Tax Days sits closer to Domicile365 on price while covering the international rules both of them lean on, so it is worth comparing all three.
Does Daysium require GPS tracking?
Automatic GPS logging is central to how Daysium builds its record, and its App Store listing notes the app may use your location even when it is not open. Tax Days offers automatic background tracking on Pro but treats it as optional: it uses significant-change monitoring rather than continuous GPS, proposes trips for you to confirm, and works perfectly well if you log every trip by hand instead.
Which app keeps my location data more private?
Tax Days stores everything on your iPhone with optional iCloud sync through Apple's CloudKit, and runs no servers of its own, so your location history never leaves your devices. Daysium is a hosted platform: your location log and photo evidence live on its infrastructure, which is what makes the concierge review and adviser portal possible.
Does Daysium cover US state residency rules?
Daysium supports configurable jurisdiction rules and counts days against thresholds you set, but it is a UK-founded product and does not ship a packaged set of all 50 US state tests. Tax Days includes all 50 states with their specific rules (New York's 184-day rule, the statutory-residence tests in NJ, MA, CT, and PA, and so on) plus the federal Substantial Presence Test.
Ready to try Tax Days?
$29.99/year. No accounts. No tracking. Free tier with limited rules.