section 21

theartfullodger

To be pedantic an s21 does not have an expiry date: It merely gives a date after which the landlord can start court action.

In Form 6a (yes I know, post 01/10/2015 tenancies..) the word "expire" (or anything starting "expir") does not occur: What it states is

You are required to leave the below address after [ ]

& for an "old fashioned" s21(4) from RLA says

We require possession of the dwelling-house known as:
____________________________________________________________________________________________________________________
____________________________________________________________________________________________________________________
____________________________________________________________________________________________________________________
After: _______________ 201__....etc etc

& from NLA says

I/we require possession of the dwelling house known as:
after ......... OR, if later, after the last day of the period of your tenancy which expires next after the end of two months from the date of service of this notice to you.

so they don't actually "expire", rather a request for possession, usually worded as "after dd/mm/yy", granting a right if valid to start court proceedings thereafter..: Perhaps Samantha's "deadline" is clearer.

But people will continue talk about s21's expiring, just as they will continue talking about s21s & s8s being "notice to quit" which they almost always aren't... and in both cases it kinda works, most of the time...

I must get out more..

Miss_Samantha

A notice period expires at some point, that's the notice's expiry date however it is phrased.

Once the notice period has expired there was no deadline by which to start proceedings. Now there is one.
After the deadline, you could say that the validity of the notice has expired.