Martin, a warm welcome to the madness that is HCMAces
Regarding (mid tax year) payroll changes, I think there would be a need to terminate/rehire in the case where the old/new payrolls are on different tax references.
This question (and the answer) popped up in another thread a couple of years ago:
http://www.hcmaces.com/forums/ubbthreads...Change#Post5698Still not 100% sure about what is meant by 'flexible retirement' though - is it a change to an employee's employment status, or is it as our Del Boy thinks, a (possibly temporary) cessation of pension contributions? If it's the latter, that wouldn't sound like a reason to terminate and rehire. Indeed, it could get a bit messy if people dip in and out as the fancy takes them!