Question

can a clerk request she is paid up to the tax band limit, even though she might work more hours than paid for?

Answer 1

No.

In this case, apply the Daily Mail test, what would it look like on the front page of the Daily Mail:

Either: Council pays senior officer cash in hand or: Council taken to court for underpaying poor hard working staff member.

Pay her what she owed, or adjust her role to fit her preferred hours, be very careful of any scheme or arrangement designed to avoid tax or cheat benefits.