Understanding Tax Residency Rules

Why Tax Residency Matters

If you split your time between two or more states — or between countries — tax residency is one of the most consequential financial questions you'll face. Get it wrong, and you could owe taxes in a jurisdiction you thought you'd left behind, face penalties for under-reporting, or miss deductions you're entitled to.

Tax residency isn't about where you want to live. It's about where the law says you live, based on objective criteria that vary by jurisdiction.

The 183-Day Rule

The most commonly cited threshold is the 183-day rule: if you spend 183 or more days in a state during the tax year, you're generally considered a resident for tax purposes. But this simple-sounding rule is full of nuance:

• What counts as a "day"? Some states count any part of a day. Others use the midnight rule (where you sleep). A few require a minimum number of consecutive hours.
• Which 183 days? Most jurisdictions use the calendar year (January 1 – December 31), but some use a rolling 12-month window or a fiscal tax year.
• Does it stack? New York, for example, has a separate "statutory residency" test that can make you a tax resident even if you spend fewer than 183 days there — if you maintain a permanent place of abode.

Domicile vs. Residency

These two concepts are often confused, but they're legally distinct:

• Domicile is your permanent, true home — the place you intend to return to. You can only have one domicile at a time.
• Residency is determined by physical presence thresholds and can apply in multiple jurisdictions simultaneously.

Changing your domicile requires more than just moving. You need to demonstrate intent through objective actions: updating your driver's license, voter registration, estate planning documents, and — critically — actually spending time in your new home state.

The Documentation Gap

Here's the problem: most people have no systematic way to prove where they were on any given day. When a state tax authority challenges your residency claim — and they do, especially for high-income taxpayers — the burden of proof falls on you.

Spreadsheets and calendars are better than nothing, but they're easily fabricated and impossible to independently verify. That's why purpose-built day tracking with cryptographic proof is becoming the standard for serious residency planning.

What You Should Track

At a minimum, document:

• Daily location with timestamps and GPS precision
• Supporting evidence: flight itineraries, hotel receipts, utility bills, lease agreements
• Domicile indicators: where your driver's license is issued, where you vote, where your primary physician is located
• Goal progress: how many days you've spent in each relevant jurisdiction, measured against the applicable thresholds

Key Takeaways

1. Tax residency rules vary significantly between jurisdictions — don't assume the 183-day rule applies everywhere the same way
2. Domicile and residency are separate legal concepts with different requirements
3. The burden of proof is on you to demonstrate your residency status
4. Systematic, verifiable tracking is your best defense against a residency audit
5. Start tracking early — reconstructing a year of location history after the fact is unreliable and legally weak