The 183-day rule, no fluff

You live between two countries. You work remote. You fly more than you actually sit at home. And one day this lands in your inbox:

“Please justify your tax residency for fiscal year 2024. You have 15 days to respond.”

If you spent 184 days in Spain, you’re a Spanish tax resident — taxed on worldwide income at 47%. If you spent 182, you’re not. The gap between the two: tens of thousands of euros.

That’s why the 183-day rule matters.

How a day actually counts (no tricks)

Any physical presence during the day = a full day.

You land at 23:50 → counts. You take off at 06:00 → counts. London–Edinburgh on the same day → one day in the UK, not two. Three-hour pit stop → one day.

The only typical exception: airside transit (you don’t leave the international zone). That doesn’t count.

What people get wrong (expensively)

Three costly misconceptions:

1. “Departure day doesn’t count, I’m already gone” — It counts. If you took off at 8AM, you were there.
2. “Three-day trips are too short to count” — Each of the three days counts.
3. “If I go to Asia for three weeks, that subtracts days from my home country” — Only if you can prove tax residency elsewhere during those weeks. The Spanish tax office calls these “sporadic absences” and counts them as days at home anyway.

The third one ruins more cases than the first two combined.

Countries count differently

Country	How it counts	Trap
Spain	Calendar year (Jan 1 – Dec 31)	“Sporadic absences” still count as days in Spain
Portugal	Any 12-month rolling window	More flexible, also more complex
Cyprus	183 days or 60-day rule with economic ties	The 60-day rule is the gateway to non-dom
UK	SRT — accumulating-tests system	16 days might be enough if you were resident recently

The question that decides your case

It’s not “did I spend more than 183 days?”. It’s:

“Can I prove, day by day, where I actually was?”

Tax authorities don’t take your word for it. They take dated documents issued by independent third parties. The strongest one is something you already have — buried in years of email:

Boarding passes are the gold-standard evidence because the airline (independent third party) issued them, the date is verifiable against the carrier’s records, and they geo-locate you.

The hard part is filing them all, dated, ready to hand over — before the letter arrives.

What’s coming in two years

Tax-residency audits don’t warn you. They land 18-36 months after the year in question.

If you had a system, you export a PDF and get on with your life. If you didn’t, you spend a month digging through six inboxes at 11pm trying to prove a trip you don’t even remember anymore.

DayProof handles the archive automatically: connect your inbox, we capture boarding passes as they arrive, classify them by year and country, and when the letter shows up you export a PDF with everything — dated, defensible, ready for the tax office.

Free during beta.