How to calculate the 180 days abroad for permanent residence in the UK? Rolling 12-month actuarial method

Many people are stuck at the permanent residence stage not because they have not completed their work or paid enough taxes, but because they have miscalculated the number of days they have left the country. Some people think that "the maximum number of days left in a year is 180 days, and it will be cleared on New Year's Eve." Returning to visit relatives, business trips, and vacations are all added up. When they apply for ILR (Indefinite Leave to Remain, permanent residence) , they find that a certain range exceeds the standard, and they wait for five years in vain. Today I will explain this algorithm thoroughly in one go.

How to calculate the 180-day rule for permanent residence in the UK?

One sentence of core rules: During your qualifying period of residence, the number of days you are away from the UK cannot exceed 180 days in any 12 consecutive months of and . Note that the key word is "arbitrary" - not by visa anniversary, nor by natural year, but a window that keeps sliding forward.

This "rolling 12-month" algorithm is applicable to most 5-year permanent residency pathways (Skilled Worker, Spouse, Global Talent, etc.) from January 11, 2018. It is much stricter than the old "cutting into segments by year" and is also the most easily overlooked pitfall.

Why does the rolling window allow people to leave the country beyond the allowed limit?

Let’s take a real scenario: You return to China for 100 days from July to November 2022, and go out for another 100 days in April 2023. Looking at it separately, both times did not exceed 180 in their respective "calendar years". But slide the window to the period from November 2022 to November 2023 , and the two times add up to 200 days - directly exceeding the standard.

The most common misunderstanding is that every 12 months, the 180-day quota will be cleared automatically. In fact, the review officer will slide the entire residency period from beginning to end, checking every possible 12-month window. If one period is exceeded, the application may be rejected.

How to count the number of days of permanent residence abroad? Does the departure day count?

Several actuarial details directly determine whether you are stuck:

🔹 only counts "whole day" : Partial days less than 24 hours are not included.

🔹 The day leaves and the day he comes back are usually not counted as departure : because you were in the UK part of the time during these two days. In other words, if you fly away on July 1st and come back on July 10th, the period from July 2nd to July 9th will actually be counted, a total of 8 days, not 10 days.

🔹 You can choose the most favorable for the review base date: the Ministry of the Interior will choose the most favorable date for you from the "application date", "any day within 28 days after the application date" and "decision date" and push back 12 months. This gives borderline applicants a little buffer.

The first step is to create an entry and exit ledger : list the "leaving date" and "returning date" of each departure in the past five years one by one. According to the passport stamp and air ticket, don't rely on memory.

In the second step, use the rolling window to check segment by segment to find the 12-month interval with the highest number of days. Manual calculations are easy to miss. You can use 永居计算器APP to record each trip. It will automatically slide the window for you and calculate to the sky. It is clear at a glance which section is the most dangerous.

The third step is, if a certain period is indeed approaching or even exceeding 180 days, don’t panic. Some "exempt" departures (such as severe natural disasters, flight interruptions caused by the epidemic, fulfillment of humanitarian rescue obligations, serious illness of immediate family members, etc.) may not be counted when there is sufficient evidence. But the threshold is very high, so be sure to keep written materials such as air tickets, medical certificates, and official notices.

Reminder: From April 8, 2026, the application fee for a single ILR is £3,226 (specifically, please refer to the latest announcement of GOV.UK). This amount of money plus the time cost of IHS and material preparation is not low. Don’t stumble on the last step of departure.

This article is for reference only. Exit exemptions and individual case circumstances vary greatly. Please consult a licensed attorney for specific questions. If you are not sure which window of your life is most dangerous, or whether a certain departure counts, you can add our lawyers to chat on WeChat.

📌 Let’s chat in the comment area: In the past 5 years, how many days did you spend most of your time abroad in the 12-month period? Have you found out after doing the math that it’s more dangerous than you thought?

If you find it useful, collect this article . Before applying for permanent residence, take it out and check it item by item for easy reference later.