The 90-night rule, and the year it finally starts to bite

Every London host I have ever spoken to knows there is "a ninety-night thing". Almost none of them can tell you where it comes from, what counts as a night, or when the clock resets.

That is a bad position to be in, because it is the sort of rule you can breach for months without anyone telling you, and then hear about from your council rather than from a blog.

So this is the plain version. I have read the actual legislation rather than a summary of a summary, and I have linked it at the bottom so you can check every line of this yourself. I would rather you did.

This is not legal advice. I sell templates; I am not a solicitor, and your building, your lease and your borough can all change the answer. What follows is what the law says and where to read it.

Where the number comes from

The rule lives in a 1973 Act about London, amended by a 2015 one. Section 44 of the Deregulation Act 2015 inserted new sections into the Greater London Council (General Powers) Act 1973, and the operative words are these:

the sum of—(a) the number of nights of use as temporary sleeping accommodation, and (b) the number of nights (if any) of each previous use of the premises as temporary sleeping accommodation in the same calendar year, does not exceed ninety

In ordinary English: letting your London home out for short stays is not treated as a change of use — and so does not need planning permission — as long as you stay inside ninety nights.

There is a second condition sitting right next to the first, and it gets forgotten. At least one of the people providing the accommodation must be liable to pay council tax at that property. The exemption was written for people letting the home they actually live in and pay tax on. It was not written for a portfolio.

What actually counts as a night

The phrase the legislation uses is temporary sleeping accommodation. The GLA's own guidance defines that as sleeping accommodation occupied by the same person for less than 90 consecutive nights in return for money.

That definition trips people up, because it puts two different ninety-night ideas in play and they are not the same thing:

• The annual limit is the one this post is about — the total nights the property is used for short stays across the calendar year.
• The ninety consecutive nights in the definition is about a single stay by a single guest, and it is part of what makes a letting "temporary" at all.

A run of ordinary weekend bookings can eat your annual ninety while no individual stay comes anywhere near ninety consecutive nights. Do not read the second number as permission to relax about the first.

The other half of the counting problem is that the limit attaches to the property, not to the platform. The GLA guidance puts it as the total number of nights that a property is used as temporary sleeping accommodation. So a year that runs:

• January — 8 nights
• March — 12 nights
• May — 10 nights
• July — 21 nights
• September — 17 nights
• October — 12 nights

is eighty nights used and ten left, whether those bookings came through one app, three apps, or a friend of a friend who paid you directly. Airbnb is counting Airbnb. Nobody is counting your year for you.

Three details that catch people out

It is a calendar year. Not a rolling twelve months, not the tax year. The count runs 1 January to 31 December and then starts again at zero. If you are at seventy-eight nights in October, you have twelve left — and a fresh ninety in January.

It is Greater London only. This particular ninety-night cap is a London rule. If you let in Cornwall or Edinburgh, this specific section does not apply to you — which does not mean there are no rules where you are, only that they are different ones. Please do not carry this number out of London and assume it holds.

The rule has an off switch. The same 2015 amendment lets a local planning authority, or the Secretary of State, direct that the exception does not apply — to particular premises or to a whole area — where that is necessary to protect the amenity of the locality. So "London allows ninety nights" is the general position, not a guarantee about your building. Your borough is the one who knows.

What happens if you go over

Past ninety nights without permission, the use stops being exempt and becomes a material change of use — which needs planning permission from your borough. Councils can and do investigate, and the risk is planning enforcement action.

I am deliberately not going to quote you a fine. Enforcement runs through the ordinary planning route, outcomes vary by borough and by case, and every confident figure I found traced back to somebody else's blog rather than to a council. If a number matters to your decision, ask your borough directly rather than trusting me or anyone else writing generally.

The part that is actually changing

Here is why this year is worth paying attention.

The government has announced a mandatory national register of short-term lets in England. Gov.uk's guidance — last updated in May 2026 — still says only that it is expected to begin in 2026, and that it is not yet in force. I looked for a firmer date and could not find one I would stand behind on a primary source, so I am not going to invent one. What I can tell you is that it is coming, that it is national rather than London-only, and that "I did not know" will be a worse answer next year than it is this year.

Alongside it, a new planning use class for short-term lets has been announced. On the government's own description, existing dedicated short-term lets would be reclassified into it without needing a planning application, and homeowners would keep the ability to let their own main or sole home for up to ninety nights a year. That announcement dates from February 2024 and the timetable has moved more than once since, so treat it as direction of travel rather than a date in your diary.

And one change that has already happened, which I still meet hosts who have not heard about: the Furnished Holiday Lettings tax regime ended in April 2025. Holiday-let income is now taxed under the ordinary rules for residential property income, without the reliefs the FHL regime used to carry. I am not going to walk you through what that means for your return — that is an accountant's job and the figures move — but if your mental model of your own tax position was formed before 2025, it is out of date.

What I would actually do about it

Count. That is genuinely most of it.

Ninety nights is not a small allowance if you are letting a spare room around your own life. It is a very small allowance if you are letting a whole flat every weekend — that is roughly a night and three-quarters a week before you are at the edge of it. Most people who breach it do so by drifting, not by deciding.

So keep a number somewhere you will see it. A note on your phone is fine. What matters is that the count exists outside the booking platform, because the platform is counting its own bookings, not your calendar year across every channel you let on.

And if you are anywhere near the line, talk to your borough before you cross it rather than after. Planning departments are much more pleasant to deal with when you are asking a question than when they are asking you one.

Before you take another booking

Worth being able to answer these without having to stop and think:

• Is the property in Greater London, so that this is the rule that applies to you?
• Is at least one person providing the accommodation liable for council tax there?
• How many short-stay nights has the property used since 1 January?
• Does that number include every channel — other platforms, direct bookings, the friend of a friend who paid you cash?
• Has your borough issued a direction that switches the exception off for your building or your area?
• If you are leasehold, does your lease allow short lets?
• If you rent, does your landlord?
• Does your mortgage lender?
• Does your insurer?
• Are you meeting the safety requirements that apply to letting to guests?

The GLA guidance is explicit that the landlord, freeholder, mortgage and insurance permissions are things to settle before you let rather than after. If more than one or two of those made you pause, that is the point to stop and check — not the point to accept the next booking.

If it helps, the short-stay agreements and welcome guides are here — the paperwork side of hosting, written to be filled in rather than admired. And if you are not sure which agreement fits your situation, I wrote a guide comparing them.

Correct as at 31 August 2026. Rules change, and this is the sort of area where they are actively changing — check the sources below for the current position before you rely on any of it.

Where this comes from

• Deregulation Act 2015, section 44 (inserting sections 25A and 25B into the Greater London Council (General Powers) Act 1973)
• Greater London Authority, "Guidance on short term and holiday lets in London"
• GOV.UK, "Letting out a self-catering holiday home in England: rules and regulations" — registration scheme status and the end of the FHL regime
• GOV.UK, "Short-term lets rules to protect communities and keep homes available" — the announced register and use class