Quick one for the landlords on here.

If you serve notice on a tenant (Section 21 notice) who is on a periodic tenancy would the following dates be correct assuming...

The original AST started 10th of the month.
Rent paid by the local council every 4 weeks.

If i need them out on August 30th can i even though it's not the anniversary of the tenancy as i've given over 2 months notice?