Postal Deeming Rules for Section 13 Rent Increases
What Postal Deeming Means for Section 13 Notices
When you serve a Form 4A rent increase notice by first-class post, the tenant does not need to physically open or acknowledge the letter for service to be legally complete. Under Section 7 of the Interpretation Act 1978, a letter sent by first-class post is deemed served two working days after posting. This legal fiction — called postal deeming — sets the official service date regardless of when the letter actually arrives at the property.
Working days exclude Saturdays, Sundays, and bank holidays. Only standard Monday-to-Friday business days count toward the two-day deeming period.
How to Count the Days
Posted on a Monday: deemed served on Wednesday (two working days later). The two-month notice period for the rent increase runs from Wednesday.
Posted on a Wednesday: deemed served on Friday.
Posted on a Thursday: deemed served on Monday of the following week (Friday is day one, Monday is day two — the weekend is skipped).
Posted on a Friday before a bank holiday Monday: Friday does not count as the posting day. Day one is Tuesday, day two is Wednesday. Deemed service: Wednesday.
The deeming date is when the two-month notice clock starts. If deemed service falls on 15 January, the earliest valid effective date for the rent increase is one that falls on or after 15 March and aligns with the start of a tenancy rental period.
Certificate of Posting: Your Proof
A Certificate of Posting is a stamped receipt you obtain at the Royal Mail counter when you hand over your letter. It records the date of posting and is free of charge. This is your primary evidence of when the letter entered the postal system.
Without a Certificate of Posting, proving when you posted the notice may be harder. If the tenant disputes the service date — or if the matter reaches the First-tier Tribunal — a vague memory of "I think I posted it around that date" carries no weight.
Ask for the certificate at the counter. The counter assistant stamps it with the date and the post office location. Keep it alongside your copy of the completed Form 4A.
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Why Not Recorded Delivery?
Recorded (signed-for) delivery seems more secure because it requires the recipient's signature. In practice, it is riskier for Section 13 notices. If the tenant is not home, delivery may be delayed while the item awaits collection.
More critically: if the tenant refuses to sign for the letter, service may be delayed or defeated.
First-class post with a Certificate of Posting avoids all of this. Service is deemed complete two working days after posting, regardless of what the tenant does. The postal system carries the legal presumption, and you have the certificate to prove your posting date.
Practical Tips
Build a buffer. If the effective date on your Form 4A is 1 April 2027, and your tenancy period starts on the 1st, you need deemed service by 1 February at the latest (two full calendar months before). That means posting by Thursday 28 January 2027 to ensure deemed service on Monday 1 February. In practice, posting a week earlier gives you room for any unexpected bank holidays or counting errors.
Check the calendar. The Christmas and Easter periods are littered with bank holidays that do not count as working days. A letter posted on 23 December may not be deemed served until 29 or 30 December, depending on when the bank holidays fall.
One letter per tenant. If you have joint tenants, post a separate Form 4A to each named tenant. A single letter addressed to both is procedurally cleaner than it sounds — but separate copies remove any ambiguity about who was served.
The Full Section 13 Process
Postal deeming is one timing element in the Section 13 procedure. You also need to verify the 52-week frequency rule, calculate the correct effective date, and complete Form 4A accurately. Our Section 13 rent increase guide includes a printable notice timeline planner that factors in postal deeming, bank holidays, and rent-period alignment so you can work backwards from your target date to the exact posting day.
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