Section 21 Notice Date - Fixed Term

[westminster]

Also, it's generally agreed that a s.21 shouldn't expire 'on' the last day of a fixed term, because that's [arguably] during the fixed term.

[Snorkerz]

Yes, I may be thinking too hard, but does it make a difference if OP's break clause notice says it expires 'after' or 'on' 1st July, d'you think?

'After' could imply that the break takes effect on 2nd July. On a s21 the 'after' does not apply to when the tenancy ends, but when the landlord can apply for possession, and the earlies that can be is the day after the tenancy ends.