Schengen 90/180 overstay exposure (EES rules, 2026)

A contract commissioning engineer with 79 Schengen days already behind her can legally stay 15 more from 5 October 2026 -- and the three-week job her Rotterdam client just booked runs 6 days past that, which prices out at EUR 29,800 once the fine and the blocked trips behind an entry ban are added up. She is not a rule-breaker. She simply counted the way almost everyone counts, by looking at the last trip instead of at a window that keeps moving.

The Schengen 90/180 rule is 90 days inside the whole area in any rolling 180-day period. Two things make it hard. The area counts as one country, so a week in Poland and a fortnight in Portugal land in the same bucket; and the window rolls, so days you spent five months ago drop out of it while you are still standing in the arrivals hall, which means your allowance can grow during a trip. Ask a chatbot and the rule usually comes back stated correctly and calculated wrong, because the arithmetic depends on which earlier days expire and when.

Until recently the consequence of getting it wrong was modest, because the evidence was a smudged stamp. That changed on 10 April 2026, when the Entry/Exit System became fully operational at every Schengen external border. ETIAS follows in the last quarter of 2026 at EUR 20. Neither system changes the 90-day cap; they remove the possibility that nobody notices.

What an overstay costs is deliberately not one number, and this is where most free day counters stop. The fine is set by each member state's national law and varies widely. The entry ban is a separate decision: under Article 11 of the Return Directive 2008/115/EC it is capped at five years, and once it is in the Schengen Information System every border officer sees it in real time. No tool can honestly print a fine table right for all of them, so the fine and the ban length are inputs you fill in from the country you exit through. What the tool does is the multiplication nobody sits down to do: ban length, times the trips this traveller makes per year, times what one of those trips is worth to the business.

Here is the worked case, the same one on the result card. Days inside in the last 180: 79. Rolling out during the trip: 4. Entry: 5 October 2026. Stay, counting entry and exit day: 21 days. Fine: EUR 1,000. Ban: 12 months. Trips per year: 6, each worth EUR 4,800. The answer comes back as 15 days allowed, a last legal day of 19 October 2026, 6 days over the cap, EUR 1,000 of fine exposure, EUR 28,800 of blocked trips and EUR 29,800 in total.

Now change one field. Drop the days used from 79 to 40 and the same 21-day trip fits: 54 days allowed, nothing over, nothing owed. Push the trip instead to 2 November 2026, stretch it to 30 days and assume a 36-month ban, and the total goes to EUR 87,400. The three answers above came out of the same function with three sets of inputs.

The free layer is the whole calculation, in the popup and on a web page running identical code. No key, no cap, no watermark, no lockout after a few runs. The paid layer sits on a different axis: the $60 licence key exports each check as a CSV row, so the working lands in the traveller's mobility file, and sets a browser alarm before the last legal day, so the next trip is checked before it is booked.

For scale: the 2026 Guideline Hourly Rates put a Grade A London 1 solicitor at GBP 579 an hour, in force since 1 January 2026. An hour of professional time spent on one question about one trip costs more than the key, and the answer expires the next time that engineer boards a plane.