US expat taxes: the day counts that decide them

The United States is unusual in taxing its citizens on worldwide income regardless of where they live. That single fact makes the US expat position more layered than most: you are dealing with a filing obligation that does not end, a set of reliefs that reduce the resulting tax, and a separate layer of state rules that pay no attention to any of it.

Almost every one of those layers turns on where you physically were, and — the part that causes trouble — each of them counts days differently.

The four counts, and how they differ

The Substantial Presence Test decides whether someone who is not a citizen or green-card holder is nonetheless a US tax resident. It weights three years of days, so a light year can still tip you over on the strength of the two before it. Any part of a day present counts as a full day.

The FEIE physical presence test asks the opposite question — how long you were away — and it demands full days, midnight to midnight, within a 12-month window you get to choose. Its counting rules are stricter in a way that surprises people: a day you fly into the United States is not a full day abroad, and neither is a day spent over international waters.

The bona fide residence test is the alternative route to the same relief, and it is not a day count at all. It asks whether you genuinely settled abroad for an uninterrupted period covering a full tax year, which means it tolerates the travel that would destroy a physical presence count.

State statutory residency runs underneath all of it. New York in particular combines a day count with a permanent place of abode, counts any part of a day, and audits the result aggressively using phone, toll and card records.

What overrides a count

Two mechanisms can displace an answer the arithmetic produced.

The closer connection exception preserves non-resident status for someone who tripped the Substantial Presence Test but kept a tax home abroad and a closer connection to that country. Note the asymmetry that catches people: the exception is judged on current-year days alone, while the test that caught them spanned three years.

Treaty tie-breakers allocate residence between two countries that both claim you, running through permanent home, centre of vital interests and habitual abode. Days feed the last of those, but rarely decide it.

Where the evidence actually matters

Every one of these tests is arithmetic over a fact pattern, and the arithmetic is the easy half. What gets tested under examination is whether you can show where you were — which days were excluded and why, which were spent working, which were spent at sea, and what supports each claim.

A count reconstructed in April from memory and boarding passes is exactly what an audit is designed to take apart. A dated, contemporaneous record with a stated source for each attribution is the thing that holds.

Planning notes

• Check the federal weighted total before booking travel, not after. The three-year reach means this year’s freedom was partly decided two years ago.
• Decide which FEIE route you are relying on before the year ends, because the physical presence route constrains travel in a way bona fide residence does not.
• Treat state residency as a separate exercise with its own evidence. Clearing the federal test tells you nothing about New York or California.
• Keep the reasons, not just the totals. Exclusions are where borderline cases are won, and a bare day count cannot defend them.