Connecting Through Miami: The Under 24 Hour Transit Rule and Your US Day Count

Does a Connection Through Miami Count as a US Day?

Not if you stay in transit and the connection runs under 24 hours. Under 26 CFR 1.937-1(c)(3)(ii)(B), a day spent in transit between two points outside the United States does not count as a day of presence in the United States for the presence test, as long as you are physically present in the United States for fewer than 24 hours. A connection through Miami, Atlanta, Dallas, Charlotte, or any other mainland hub qualifies the same way. The rule is not really about Miami. It is about the transit activity and the clock.

That one sentence covers most connections. Two things determine whether it covers yours: what "in transit" actually requires, and how the 24 hours gets measured.

The Rule Itself

The presence test asks how many days you were present in Puerto Rico, and in some versions of the test, how many days you were present in the United States. 26 CFR 1.937-1(c)(3) lists the days that do not count toward either side of that count, and the transit exclusion sits in that list. A day in transit between two points outside the United States, with physical presence in the United States under 24 hours, is excluded.

It is not the only excluded category. The same paragraph excludes days present in a possession because of a family member's medical condition that arose while you were there, and days present in the United States because of a federally declared major disaster. The transit exclusion is narrower than either of those, and more mechanical. It turns on two conditions you can check against your own itinerary: the activity requirement and the time limit.

What Counts as "In Transit"

The 24 hour figure matters, but it is not the whole test. 26 CFR 301.7701(b)-3(d), which 1.937-1 cross references for the definition of "in transit," requires that your activity in the United States be substantially related to completing travel to a foreign point of destination.

The regulation gives its own example. An individual who travels between airports in the United States to change planes on the way to a foreign destination is in transit. That is the ordinary connection: land, walk or shuttle to the next gate, board, keep going. But attend a business meeting while you are present in the United States, whether or not that meeting happens inside the airport, and you are not in transit for that day. The activity breaks the exclusion, not the location.

Practically, this means the connection has to stay a connection. Staying in the terminal, moving between one flight and the next, keeps the exclusion intact. Step out of the secure area for a meeting, an errand, anything unrelated to completing the trip, and that day goes back on the board as a day of US presence, regardless of how long you were actually there.

How the 24 Hours Is Counted

The window is a continuous 24 hours, from the moment you're physically present in the United States to the moment you leave. It doesn't reset at midnight. A connection that begins at 11 PM and clears by 10 PM the following day touches two calendar dates but still sits under 24 hours of physical presence, so the exclusion still applies if the activity requirement is also met.

The reverse holds too. Let a connection run long, whether from a missed flight, a mechanical delay, or a weather hold, and if your physical presence in the United States reaches 24 hours or more, the exclusion no longer applies to that stay. 26 CFR 1.937-1 carves out no exception for the reason behind the delay. A day added by an airline's schedule counts the same as a day added by choice.

Why This Matters Most for the 90 Day Test

Publication 570 lays out several ways to satisfy the presence test: 183 days present in the relevant territory during the tax year, 549 days across the current year and the two before it with at least 60 in each, no more than $3,000 of US source earned income combined with more days in the territory than in the United States, or no more than 90 days present in the United States during the tax year. See the five ways to pass the presence test for the full comparison.

The transit exclusion matters most if you're relying on that last option, the 90 day US presence test. Ninety days is a thin allowance for a year of travel, and a traveler who routes through mainland hubs regularly has the least room for a connection to go wrong. A single disqualified day, whether from a delay that pushed past 24 hours or from stepping out of the terminal for a meeting, is a full day against that cap. Someone counting toward 183 days in Puerto Rico can usually absorb an extra US day without much consequence. Someone counting toward 90 days in the United States cannot.

How This Fits Into the General Presence Rule

Absent an exclusion, the default rule is broad: you're treated as present in a location on any day you're physically there at any time during that day, even for a few minutes. That's the same general rule that governs what counts as a day in Puerto Rico on the territory side of the count. The transit exclusion is a narrow carve out from that default, built for a traveler whose itinerary happens to route through the United States with no intention of doing anything there but change planes.

That's also why the activity requirement exists. Without it, you could spend an entire day conducting business in the United States and still claim the exclusion just by keeping the visit under 24 hours. The regulation closes that gap by tying the exclusion to genuine transit, not just to the clock.

Documenting a Qualifying Connection

Keep the boarding passes and the itinerary for every connection you plan to exclude. The record should show your arrival and departure times at the connection point, which is what demonstrates the stay ran under 24 hours, and it should read as a straight connection rather than a stopover with unrelated activity mixed in.

This isn't a heavy lift for most travelers. Airlines already generate this paperwork. Keeping the ledger by hand, across a year of connections in multiple countries, is the part people abandon by spring. One83 builds it from your calendar, connection times included, so the record exists before anyone asks for it.

Frequently Asked Questions

Does a layover in Miami count as a US day if it's under 24 hours?

Not automatically. It is excluded only if you stay in transit the whole time, meaning your activity in the United States is limited to what is needed to complete travel to your foreign destination, such as changing planes. If you leave the airport for a business meeting or any unrelated activity, the day counts as US presence even if you are there for less than 24 hours.

How is the 24 hours measured?

The 24 hour window runs from the moment you are physically present in the United States to the moment you leave, measured continuously, not by calendar day. A connection that starts at 11 PM and clears by 10 PM the next day, for example, is still under 24 hours even though it touches two calendar dates.

What if my connecting flight is delayed past 24 hours?

If your physical presence in the United States stretches to 24 hours or more, the exclusion no longer applies for that stay, regardless of the reason for the delay. The regulation does not carve out an exception for weather, mechanical delays, or missed connections.

Does this exclusion apply to connections through any US airport, or just Miami?

It applies to any point in the United States, not just Miami. Miami, along with other hubs like Atlanta, Dallas, Charlotte, and New York, is simply one of the most common mainland connection points for travelers moving between Puerto Rico and international destinations.

Do I need to document a qualifying transit day?

Yes. Keep your boarding passes and itinerary showing arrival and departure times at the US connection point. If you are ever asked to substantiate your day count, this is the paper trail that shows the connection stayed under 24 hours and that you did not leave the transit area for unrelated activity.

The Short Version

A connection through Miami or any other mainland hub doesn't cost you a US presence day if you stay in transit and clear it in under 24 hours. Both conditions matter. The activity has to stay confined to completing your trip, and the clock runs continuously from arrival to departure, not by calendar day. Track this closely if you're relying on the 90 day US presence test rather than the 183 day count in Puerto Rico, where a single miscounted connection has far less room to absorb.

One83 is a tracking tool, not tax advice. Consult a licensed tax professional about your situation.