Rent Increase Notice Period Wales: The Two-Month and 12-Month Rules
Two Separate Timing Rules
Welsh landlords face two non-negotiable timing requirements under Section 123 of the Renting Homes (Wales) Act 2016. Both must be satisfied, and getting either one wrong by a single day invalidates the entire rent increase notice.
Rule 1: Two calendar months' notice. The contract-holder must receive Form RHW12 at least two full calendar months before the new rent takes effect. The clock starts from the date service is deemed to occur, not from the date you post the letter.
Rule 2: Once every 12 months. The new rent cannot take effect within 12 months of the previous rent variation. The 12-month interval is measured from the date the last increase took effect — not from the date the previous notice was served.
How Deemed Service Affects the Calendar
The two-month window runs from when the notice is legally deemed served, which varies by delivery method:
| Method | Deemed served |
|---|---|
| Hand delivery | The day you hand it over |
| First-class post | Second business day after posting (excludes Sundays and bank holidays) |
| Email (with prior written consent) | Day of transmission if sent before 16:30 on a business day; otherwise the next business day |
Worked Example: First-Class Post
You post Form RHW12 on Monday 14 September 2026. Deemed service is Wednesday 16 September. The two calendar months run through 16 November. The earliest valid effective date is 17 November 2026 — or the next rent-due date after that, depending on your contract.
Worked Example: First Increase After Occupation
The contract starts on 1 December 2025. The 12-month rule means the earliest effective date is 1 December 2026. Because you need two months' notice, you can serve Form RHW12 as early as late September 2026 — specifying 1 December 2026 as the effective date.
The First Increase on a Converted Contract
If the occupation contract is a converted AST (originally created before 1 December 2022), any rent variation under the old Section 13 of the Housing Act 1988 that took effect before conversion counts as a prior variation for the 12-month calculation. Check your records for the date the last increase took effect — that is month zero.
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Practical Buffer
Because post takes a couple of days and deemed service adds another two business days, building in a buffer of three to five extra days beyond the minimum two months protects you against bank holidays, postal delays and weekends that shift the deemed service date.
The Wales Rent Increase Guide includes a date calculation worksheet where you enter the contract start date, the service method and the planned posting date, and the guide returns the earliest valid effective date.
What Happens If You Get It Wrong
A notice served with less than two months or specifying an effective date within 12 months of the last increase is legally defective. The contract-holder can continue paying the existing rent, and any "arrears" claimed above the existing figure are unenforceable. You would need to start the process again with a fresh Form RHW12 and a compliant effective date.
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