FREE STATUTORY CALCULATOR · HOUSING ACT 1988 S.13 & SI 2026/354
Section 13 (Form 4A) Earliest Valid Start Date Calculator
Under section 13 of the Housing Act 1988 (as amended by the Renters' Rights Act 2025 from 1 May 2026), an error of even one day in Box 4.6 of Form 4A invalidates your rent increase notice. Enter your tenancy dates and service method below to calculate the earliest lawful start date across all four statutory rules.
Statute-aligned self-service software publishing tools mapped to the Housing Act 1988 (as amended by the Renters' Rights Act 2025), Tenant Fees Act 2019, SI 2026/324, SI 2026/354, and SI 2026/421. Operated by Ditra (established in Spain) — [email protected].
Earliest valid Form 4A Box 4.6 date
1 February 2027
Box 4.6 entry: 01022027 (DDMMYYYY)
Increasing rent from £1,400.00 per month to £1,500.00 per month (+£100.00 / +7.1%)
| Statutory Rule | Authority | Calculated Date | Status |
|---|---|---|---|
| 0. Deemed Date of Service | Form 4A Note to Landlord (Hand it to the tenant in person) | 1 November 2026 (Dispatched 1 November 2026) | Baseline clock start |
| 1. Minimum 2 Months' Notice | Housing Act 1988 s.13(2)(a) | 2 January 2027 | Earliest date after 2 clear calendar months |
| 2. 52-Week Initial Tenancy Floor | Housing Act 1988 s.13(2)(b) | 31 May 2026 | 52 weeks (364 days) from 1 June 2025 |
| 3. 52/53-Week Previous Increase Floor | s.13(3A)–(3B) & SI 2026/421 reg 7 | Not applicable (first increase) | No prior increase recorded |
| 4. Next Rent Period Start Alignment | s.13(2) & Form 4A Note A4 | 1 February 2027 | Snapped to next per month period start anchored to 1 October 2026 |
Common questions
Why does postal or email service add working days?
Deemed service for Section 13 notices served by post or under a tenancy-agreement method typically adds a buffer of two working days after the dispatch date before the minimum notice period starts counting, which this calculator applies before the two-month rule.
What is the 52-week floor in section 13(2)(b)?
Where the rent was previously increased by a valid Section 13 notice, Tribunal determination, or certain pre-2026 review clauses, Box 4.6 cannot start earlier than 52 weeks (364 days) after the last increase took effect.
When does section 13(3B) use 53 weeks instead of 52?
If measuring back from the anniversary of the first increase after 11 February 2003 leaves a gap of more than six days, the minimum interval for that year becomes 53 weeks (371 days) rather than 52 weeks, to stop annual drift on weekly or four-weekly periods.
Which Form 4A version does this follow?
Outputs are aligned to GOV.UK Form 4A as published under SI 2026/354 (version 05.26), including Box 4.6 DDMMYYYY entry formatting for the earliest lawful start date.
SignWise is a self-serve document preparation service operated by Ditra (established in Spain). SignWise is not a law firm, is not regulated by the Solicitors Regulation Authority (SRA), does not provide legal advice, and does not carry on reserved legal activities under the Legal Services Act 2007 (section 12 and Schedule 2, paragraph 5). You prepare your document from your answers, review it carefully, and sign it yourself. SignWise is not responsible for legal outcomes. Seek independent legal advice if you are unsure whether a document suits your property or circumstances.
Deterministic Statutory Calculation Notice (Legal Services Act 2007): This calculator applies mathematical formulas and statutory date rules from primary and secondary legislation in force in England (Housing Act 1988, Housing Act 2004, Tenant Fees Act 2019, Renters' Rights Act 2025, SI 2026/324, SI 2026/354, and SI 2026/421) directly to the figures and dates you enter. It provides general statutory information and automated mathematical outputs only. It does not constitute legal advice or a reserved legal activity under section 12 and Schedule 2, paragraph 5 of the Legal Services Act 2007. If your tenancy involves complex transitional notices served before 1 May 2026 or disputed service clauses, consult a regulated solicitor.