How it works
You need an ETA (Electronic Travel Authorisation) to travel to the UK. It costs £20, you apply online or in the UK ETA app, and you usually get a decision within a day (it can take up to 3 working days).
An ETA lasts 2 years or until your passport expires, whichever comes first, and covers as many trips as you like in that time. It does not guarantee entry, the officer still decides.
Each visit can be up to 6 months. The UK does not add your days up over a rolling period.
The limit on back to back stays is the genuine visitor test: you must leave at the end of each visit and not "live in the UK for extended periods through frequent or successive visits, or make the UK your main home."
The UK, Ireland, the Channel Islands and the Isle of Man form the Common Travel Area. There are no immigration checks on the land border with Northern Ireland, but UK rules still apply, so you still need an ETA to cross into Northern Ireland unless you live in Ireland.
An example
You land in London on 1 March 2026 with your ETA. You can stay up to 6 months, so you need to leave by the end of August. You spend September and October in Schengen, then fly back to the UK on 1 November for Christmas with friends. Nothing in the rules sets a number of days you must be away, but the officer may ask why you are back so soon, where you live and when you will leave, and six months in, two out, six in again starts to look like living in the UK.
Mistakes people make
- Showing up without an ETA. Airlines, ferries and trains can refuse to board you.
- Treating 6 months as a yearly allowance you can refill forever. Repeated long visits can get you refused as not a genuine visitor, even though no day count is broken.
- Thinking Ireland is a way around the ETA. The exemption is only for people who live in Ireland and arrive from Ireland, Guernsey, Jersey or the Isle of Man, and they must carry an original Irish government document like an Irish Residence Permit or driving licence. A US tourist visiting Ireland still needs an ETA for the UK.
- Mixing up UK and Schengen time. They are separate clocks. Days in the UK do not count toward Schengen, and leaving Schengen for the UK does not reset Schengen days you have already used.
- Working remotely for a UK client or business. Visitors cannot work for a UK organization, so be careful describing your trip as work.
Quick answers
How long can a US citizen stay in the UK?
Up to 6 months each time you enter, and you need a UK ETA before you travel.
How much is a UK ETA and how long does it last?
It costs £20 and lasts 2 years or until your passport expires, whichever comes first. It covers as many trips as you like in that time.
Can I leave the UK and come right back?
No rule sets a number of days you must be away, but you have to be a genuine visitor. Long stays back to back can get you refused, even if no day count is broken.
Do UK days count toward Schengen?
No. They're separate clocks, and a trip to the UK doesn't reset Schengen days you've already used.
Where this comes from
Government sources only. Read the rule yourself.
- Get an electronic travel authorisation (ETA), GOV.UKgov.uk ↗
- Immigration Rules Appendix V: Visitor, GOV.UKgov.uk ↗
What changed
3 Oct 2026. Checked against GOV.UK. No change to the rules.
A plain-language summary of the official rules. It isn't legal advice. If your situation is unusual, confirm with the relevant authority or a qualified adviser.
