Get the dates right. Keep the notice valid.
The Renters’ Rights Act rewrote the rules for every assured tenancy in England – and most of the new traps are date arithmetic. TenancyTools.uk gives landlords and tenants free calculators that apply the statutory rules exactly, with plain-English guides that explain what changed and why it matters.
Calculators
Five free calculators that apply the Renters’ Rights Act rules to your own dates and figures. Pick the one that fits your situation – each shows its working.
Section 13 Rent Increase Date Calculator
Our most-used tool. Enter the service date, rent due date and last increase to find the earliest valid effective date for Form 4A – the two months’ notice rule, rent period rule and 12-month gap applied together.
Use the calculator →Section 13 Notice Validity Checker
Run a Form 4A notice through the form, service and date checks that make or break a rent increase, and see point by point whether it stands up.
Use the checker →Rent Arrears Threshold Checker
Enter the rent and arrears to see whether the mandatory Ground 8 possession threshold is met – three months’ rent, or 13 weeks’ for weekly tenancies.
Use the checker →Tenant Notice to Quit Date Calculator
Enter your notice date and rent due day to find the earliest valid date you can end an assured periodic tenancy.
Use the calculator →Rent Increase Tribunal Deadline Calculator
Challenging a rent increase? Enter the effective date on the notice to find your deadline to refer it to the First-tier Tribunal.
Use the calculator →Guides
Plain-English explainers for the rules that changed on 1 May 2026, written for landlords and tenants rather than lawyers. Each links to the Section 13 rent increase date calculator that does the date work for you.
- How to serve a Section 13 notice, step by step
- What makes a Section 13 notice invalid?
- How to challenge a rent increase at the First-tier Tribunal
- Rent review clauses are void: what landlords should do instead
- The 12-month rule explained
- Phase 2 preview: the PRS Database and the Ombudsman
What the Renters’ Rights Act changed
The Act came into force on 1 May 2026 and reshaped almost every stage of a private tenancy in England. Fixed terms are gone: all assured tenancies are now monthly periodic, whatever the agreement says. Section 21 “no-fault” evictions were abolished, so possession now runs through the amended Section 8 grounds. And the rules around rent changed fundamentally:
- Rent review clauses are void. Index-linked and fixed-uplift clauses in tenancy agreements no longer have any effect, even in agreements signed before the Act.
- Section 13 is the only route. A rent increase is only valid if served on the prescribed Form 4A with at least two months’ notice, taking effect on a rent due date.
- Once a year, and no sooner. The new rent cannot take effect until at least 52 weeks after the last increase – or 12 months after the tenancy started for a first increase.
- Challenges are risk-free for tenants. The First-tier Tribunal can no longer set a rent higher than the landlord proposed, so a tenant who challenges has nothing to lose but the fee.
More change is coming: Phase 2 of the reforms, expected later in 2026, introduces the Private Rented Sector Database and a new Ombudsman scheme. We will publish tools and guides for each phase as the rules are confirmed.
Why the dates matter so much
Under the old rules, a defective rent increase notice was an inconvenience. Under the new rules it is expensive. A Section 13 notice with an effective date even one day too early is invalid in its entirety: the increase does not happen, and the landlord must serve a fresh Form 4A and wait out a new two-month notice period. On a typical increase that is hundreds of pounds of rent lost to a date error – and because the courts treat the contractual rent due date, deemed service rules and the 52-week gap strictly, the arithmetic is easy to get wrong by hand. That is the problem this site exists to solve.