London 90-Day Rule Explained: Short-Let Limits & Compliance

If you are letting a London flat on Airbnb, Booking.com, Vrbo or any other short-term platform, you are operating inside one of the most specific — and most misunderstood — regulatory regimes in the UK. The "90-day rule" is shorthand for Section 25 of the Deregulation Act 2015, which permits short-term letting of a London residential property for up to 90 nights in a calendar year without planning permission for change of use. Cross 90 and you are, by default, operating an unauthorised change of use. This post explains exactly what the rule covers, what counts as a short let, how operators legally extend revenue beyond the cap, what the fines look like, and how Big Ben Suite tracks compliance for every managed unit.

The GLA 90-day rule, precisely

Section 25 of the Deregulation Act 2015 amended Section 25A of the Greater London Council (General Powers) Act 1973. The amendment created a statutory exception: short-term letting of residential premises in Greater London is no longer a material change of use requiring planning permission, provided the property is let for no more than 90 nights in total in any calendar year, and the person providing the accommodation is liable for council tax on the property.

• The cap is 90 nights per calendar year (1 January to 31 December), not 90 days per booking.
• The cap applies to the property, not the owner — selling the flat does not reset the counter.
• The person offering the accommodation must be liable for council tax — otherwise the exception does not apply at all.
• The rule applies across the whole of Greater London — every London borough.

What counts as a short let?

A "short let" for the purposes of the 90-day rule is any stay of 90 nights or fewer provided on commercial terms. Critically, the following do not count toward the 90:

• A single booking of 91 nights or more by one guest (this is the core of the mid-term switch strategy).
• Any tenancy granted under the Housing Act 1988 — a standard AST or periodic tenancy.
• A stay where the premises are shared with the host (the traditional Airbnb "home-share").
• Corporate relocations structured as licences for 91+ consecutive nights to a single organisation's nominee.

How operators navigate the cap — the mid-term switch

The Hybrid-Let model treats 90 as the design limit for the short-let channel. The remaining ~275 nights per year are filled with stays that fall outside the cap. The operational pattern is:

1. Front-load short-let nights into the highest-demand windows (summer, Christmas, Easter, major events).
2. Pause the short-let listing once cumulative nights hit ~75 (Big Ben internal soft-cap, 15-night safety margin).
3. Switch the unit onto mid-term channels (SpareRoom, Silverdoor, Nestpick, direct corporate relocations) for 30–90 night consecutive bookings.
4. Accept at least one booking in the year of 91+ consecutive nights to a single guest — which extends the legal runway if the short-let soft-cap is approached.

Fines and enforcement

Enforcement is carried out by individual London boroughs' planning teams, not by the GLA centrally. Westminster, Camden, Kensington & Chelsea, Tower Hamlets, and Southwark have historically been the most active. The escalation path:

• Planning Contravention Notice — requires the owner to supply booking data within 21 days.
• Enforcement Notice — requires the unauthorised use to stop within a specified period, typically 28 days.
• Breach of Condition Notice — criminal offence if ignored.
• Prosecution — fines of up to £20,000 per offence on summary conviction, unlimited on indictment.

Airbnb itself auto-limits listings to 90 nights per calendar year in Greater London (the platform does this via its host tools), but this only covers one listing — an owner running the same flat across Airbnb, Booking.com and Vrbo can easily breach the cap across platforms while each individual listing shows under 90. Boroughs know this and cross-reference.

Borough-by-borough — does the cap vary?

The 90-night cap is set at the London level and applies uniformly across all 32 boroughs plus the City of London. However, boroughs vary in (a) enforcement appetite, (b) additional licensing that can layer on top (e.g. selective licensing, HMO licensing, Article 4 directions), and (c) whether they operate a registration scheme. The table below is a current snapshot; owners should always verify on their own borough's website.

Compliance checklist for self-managing owners

1. Confirm you are the person liable for council tax on the property (the 90-day exception requires this).
2. Keep a single master calendar that reconciles every platform — Airbnb, Booking.com, Vrbo, direct — into one nightly count.
3. Set a soft-cap alert at 75 nights so you have a 15-night buffer to switch channels.
4. Verify EPC rating is at least E (C from 2028 on new tenancies under the current roadmap).
5. Annual Gas Safety check; 5-yearly Electrical Installation Condition Report.
6. Smoke alarm on each storey, carbon monoxide alarm in every room with a solid-fuel or gas appliance.
7. HMRC: report short-let income on your Self Assessment. Post-FHL, treat as ordinary property income.
8. Mortgage: confirm your lender permits short-lets. Many residential and some BTL products do not.
9. Lease: confirm the headlease permits short-lets. Many long leases in prime London explicitly prohibit them — this is the single most common owner failure.
10. Insurance: standard home/BTL insurance will not cover short-let guests. Specialist cover (e.g. from Guardhog, Superhog-partnered insurers) is essential.

How Big Ben Suite handles the 90-day rule

Every managed property is enrolled in our internal compliance dashboard on day one. The dashboard:

• Ingests calendars from every live channel and produces a single canonical nightly count.
• Triggers a soft-cap alert at 75 short-let nights and a hard-stop at 85, forcing the unit to mid-term.
• Holds copies of EPC, Gas Safety, Electrical, lease consent, mortgage consent, and specialist insurance certificate.
• Logs every stay's duration and category, so the 91+ night exempt stays are counted against the right bucket.
• Generates an annual compliance pack for the owner's accountant — Self Assessment ready.

This is not a value-add; it is the product. Hybrid-Let only works if the compliance never slips.

What the dashboard looks like in practice

Owners receive a monthly compliance email with four fields: short-let nights booked year-to-date against the 90-cap, certificate expiry dates flagged if within 90 days, any guest incidents logged, and the canonical calendar reconciliation across all channels. The email is boring on purpose — no news is good news. When something does need attention (a certificate is due, a booking pattern threatens the cap, a lease-consent renewal is pending), it is flagged early enough that the fix is administrative rather than an emergency. This predictability is the single most valuable feature of the service, and it compounds: owners who never have a compliance scare renew indefinitely.

What happens if a borough does knock on the door

Planning enforcement in the active boroughs typically opens with a letter or a Planning Contravention Notice requesting booking data. On a managed Big Ben Suite unit, the compliance pack answers the notice in full: night counts by channel, 91-plus exempt stays, certificate history, and lease/mortgage consent copies. In every case we have handled to date, producing that pack has ended the enquiry. The enforcement teams are not looking to prosecute compliant operators; they are looking for unregistered ghost-hotels running 300 nights a year on Airbnb. Presenting a clean paper trail takes the unit off the list.