Calculators
Every calculator applies the statutory rules under the Housing Act 1988 as amended by the Renters’ Rights Act 2025, runs entirely in your browser, and shows its working so you can check the result. All tools are free with no sign-up. New calculators are added regularly as the reforms roll out.
Section 13 Rent Increase Date Calculator
The flagship tool. Enter the date Form 4A will be served, the day rent is due and the date of any previous increase, and get the earliest lawful effective date for the new rent – with the two months’ notice rule, rent period rule and 12-month gap applied together and the binding constraint identified. Includes worked examples and the five date errors that most commonly void notices.
Use the calculator →While more calculators are in development, our plain-English guides cover the same ground in detail – including how to serve a Section 13 notice step by step, what makes a notice invalid and how tenants challenge a rent increase at the tribunal.