Counting days: how Travllr keeps track of where you have been
How the Schengen 90/180 rule really works, why residency and tax day counts are easy to get wrong, and how Travllr tracks days per country so you stop guessing.
If you travel a lot, sooner or later someone asks how many days you have spent in a country, and the honest answer is "about". Counting travel days sounds trivial until a border officer, a tax office or a visa rule needs the exact number. Travllr is an app for iOS and Android that keeps a precise record of the days you spend in each country, so the Schengen 90/180 window, residency thresholds and passport expiry dates are tracked instead of guessed.
We like it because it takes a boring, fiddly problem seriously. This post explains the problem properly, starting with the rule most travellers misunderstand, and then looks at how an app like Travllr approaches it.
The Schengen 90/180 rule, explained properly
If you are not an EU citizen and you visit the Schengen area on a short stay (visa-free or with a short-stay visa), you can spend at most 90 days in any 180-day period. People usually remember the numbers and forget the word "any". That word is where the trouble starts.
The 180 days are not a fixed half-year. They are not January to June. They do not start on the day you first arrived. The window is rolling, and it looks backwards: on any given day, you take that day and the 179 days before it, count how many of those days you were inside the Schengen area, and the total must not be more than 90. Tomorrow the window moves forward by one day, and the check happens again.
A few details make the counting harder than it looks:
- Entry and exit days both count. Fly in on a Monday evening and out on a Friday morning and you have used five days, not three and a half.
- All Schengen countries share one counter. Two weeks in Spain, a weekend in Portugal and a month in Germany all come out of the same 90.
- Old days fall out of the window one at a time. A long stay seven months ago no longer counts. A long stay five months ago still counts in full, and it will keep counting until each of its days slides past the back edge of the window.
- The check applies to every day of the stay, including future ones. Being under 90 on the day you arrive is not enough. You need to stay under 90 on every day until you leave.
That last point catches people. Say you arrive with 20 days left and plan a three-week trip. You might assume you have exactly enough. But if none of your old days drop out of the window during those three weeks, you run out on day 20 and the last day is an overstay. If some old days do drop out, you might have more room than you thought. You cannot tell without working through it day by day.
A worked example
The drawing at the top of this post shows a made-up case. Looking back 180 days from today, there are three earlier stays of 21, 30 and 18 days, plus the current trip, now six days in. That is 75 days used, so 15 left today.
There is also an older 14-day stay further back. It sits outside the window now, so it no longer counts. A month ago, some of those days would still have been inside the window, and the same traveller would have had less room. This is what "rolling" means in practice: your allowance changes every single day, even when you are sitting at home.
Now suppose this traveller wants to stay another three weeks. Whether that works depends on when the 21-day stay near the back of the window started, because those days will start dropping out one by one. It might be fine. It might run out by two days. Doing this with a calendar and a pencil is possible, and people do it, but it is exactly the kind of arithmetic that goes wrong at the end of a long trip when you are tired and booking a flight on your phone.
The European Commission publishes an official short-stay calculator for this reason. It is useful, but you have to type in every entry and exit date yourself, every time.
Residency and tax days are a different count
Schengen is the rule most people have heard of, but it is not the only day count that matters. Many tax systems use physical presence as one of the tests for whether you are resident, and 183 days is a number that appears in a lot of them, and in many tax treaties.
The problem is that the rules count differently. Some use the calendar year. Some use the tax year, which is not always January to December. Some look at any 12-month period. Some count a day if you were present at midnight, others if you were there for any part of it. The United States substantial presence test, for example, adds all of your days this year, a third of last year's days and a sixth of the year before. A person who spends about four months a year in the US every year can end up over the line without ever spending 183 days there in a single year.
For people with more than one home, or who spend long periods in two or three countries, these counts run side by side. The same trip can count towards one country's threshold and away from another's. Travllr's approach is to let you set up home, dual-residence and roaming categories, so that complicated living arrangements stay readable and each count is visible on its own.
Why guessing is risky
Most people track travel in their head, in a notes app or in a spreadsheet they update when they remember to. That works until the stakes go up.
Overstaying in the Schengen area can lead to fines, an entry ban or trouble getting visas later, and the EU's Entry/Exit System now records entries and exits of non-EU short-stay travellers electronically at the external border. That record of your days exists either way. It is better if yours matches theirs.
On the tax side, the risk runs the other way too. If a tax office asks you to show you were not present long enough to become resident, "I think it was about 170 days" is not evidence. A dated record kept as you go is much more convincing than one reconstructed from memory and old boarding passes a year later.
Then there are documents. Passports need a certain amount of validity left for many entries, visas expire, and residence permits need renewing. None of that is hard to track, but it tends to be remembered at the airport.
How Travllr approaches it
Travllr counts days per country and keeps them in one chronological record across years. There are two ways to get days into it. Location-assisted records build the timeline automatically, and manual entries let you add or correct trips when the automatic record is wrong or incomplete, for example for travel before you installed the app. You can also add upcoming trips.
On top of that record it tracks the thresholds that matter: the Schengen 90-in-180 window, residency and tax day counts, and expiry dates for passports and visas. Smart alerts warn you before you reach a limit, rather than after. A visa vault keeps travel documents next to the trips they belong to, with document scanning to make setup faster.
The design goal is stated plainly on the site: to answer the questions frequent travellers actually have. How long have I been here? What window am I inside? When does the next threshold arrive? Can I prove my travel history later? That is a good list, and it is a narrow one. The app is a day counter and a record, not a travel planner or a booking tool.
It also has a small Tetris game in it, playable with the arrow keys or WASD, for when you are waiting at a gate. We mention it because it is a nice example of a serious tool being allowed one small, unserious corner.
Privacy and what the app does not do
An app that knows where you have been is holding sensitive data, so the privacy stance matters as much as the features. Travllr says it has no third-party ads, does not sell personal information and does not track you across other apps. The details are in its privacy policy, which is worth reading for any app you give location access to. Requests for data deletion go through its support page.
The other thing it is clear about: it records and calculates, but it does not decide your legal, tax or immigration status. We would say the same. Nothing in this post is legal or tax advice either. Immigration rules have exceptions (bilateral agreements, long-stay visas, residence permits) and tax residency usually depends on more than a day count, such as where your home, family and work are. If a number is close to a threshold, a good record is what you bring to a professional, not a replacement for one.
We spend our own time building mobile apps and desktop tools, and the ones we admire tend to have this shape: one job, done precisely, with the data staying yours. If you cross borders often, keep a record from today, even a rough one. The day you need it will be months from now, and it will ask about a date you have already forgotten.