15/09/2026
If you still pay your PAYE by cheque through the post, this month's deadline is Saturday.
HMRC wants cheque payments to have reached them by the 19th of the month. This month the 19th is a Saturday, so in practice the envelope needs to be gone a couple of days earlier than you might be used to.
If you pay electronically you have got until the 22nd, same as always.
I have not dressed this up. Both dates are on GOV.UK, under Pay employers' PAYE, and that is the whole post.