Deposit Cap Calculator — 5 / 6-Week Rule (UK 2026)

Section 51 of the Tenant Fees Act 2019 (in force 1 June 2019 in England) put a hard ceiling on the amount of cash a landlord or letting agent can take as a tenancy deposit. The cap depends solely on the total annual rent: under £50,000 the maximum is five weeks’ rent, at £50,000 or above it rises to six weeks. Anything above the cap is a "prohibited payment" under section 1, must be returned to the tenant on demand, and blocks any Section 21 service until the excess has been repaid.

The mechanic is calendar-week based. The Act defines weekly rent as the annual rent divided by 52. So for a £1,500/month tenancy the annual rent is £18,000, the weekly rent is £346.15 and the five-week cap lands at £1,730.77. Any deposit advertised at "£2,000 — equivalent to four weeks’ rent rounded up" is over the cap by ~£270, even though it sounds smaller than the historical six-week norm. Tools that quote a deposit by month rather than week often slide over the cap by accident.

The £50,000 threshold is annual rent for the property, not per tenant. A four-bedroom HMO let on a single joint tenancy at £4,200/month annualises to £50,400 and qualifies for the six-week cap (£5,815). Convert the same flat to a per-room AST of £1,050/month each and every tenancy individually annualises to £12,600 — under the £50k threshold and capped at five weeks (£1,211). The total deposit pool drops from £5,815 to £4,846 even though the rent collected is identical. This is why HMO and student-let portfolios typically anchor on the per-room arithmetic when sizing wear-and-tear risk.

Enforcement sits with the local authority’s Trading Standards team, with civil penalties up to £5,000 for a first breach and unlimited fine plus prosecution for repeat offending. The tenant has independent rights: they can recover the over-cap excess via the First-tier Tribunal under the Act’s recovery mechanism, and the same breach blocks Section 21 service under section 17. A landlord who took a six-week deposit on a sub-£50k tenancy in 2019 and renewed the AST in 2022 without refunding the excess is still on the hook in 2026 — the breach does not expire on tenancy renewal.

Holding deposits sit under the same Act but in a separate cap. Section 4 limits a holding deposit to one week’s rent. The holding deposit must be returned within seven days of either accepting the application (and rolling it into the final tenancy deposit), or rejecting it (with documented reasons). Quoting a "£500 holding fee" on a property where weekly rent is £346 is over-cap and a prohibited payment in its own right. The Tenant Fees Act 2019 was the first piece of UK lettings legislation to actively police pre-tenancy charging, and it is still the most-fined: 2024 MHCLG enforcement data shows it generated more landlord and agent fines than any other piece of compliance law in the residential market.

The cap also interacts with the Renters’ Rights Act 2025. The RRA does not move the cap itself — five and six weeks remain — but it does change how often you set it. Every tenancy from 1 May 2026 starts as a periodic assured tenancy. There is no fixed term to renew, so the only event that can prompt a recalculation is a Section 13 rent increase→ that pushes annual rent across the £50,000 threshold. If you take a five-week cap on a tenancy at £4,000/month and increase the rent to £4,200/month two years later, you can take an additional one week’s rent as deposit (top-up). Conversely, a downward variation does not entitle you to refund the difference automatically, the deposit can stay as-is provided it remained lawful when collected.