I recently dropped down to a 4 day week doing 32 hours a week. I think my holiday should be 22.4 days a year. That’s pro rata from a standard 28 days However the business is very seasonal and when we’re really busy I’ll have do do a 5 day week with 40 hours. Am I right in thinking that when I’m doing the longer hours I should be accruing holiday at standard rate. These longer weeks could be as many as 20 weeks so could be an extra 2 days or so worth of holiday I’m due. Many thanks

Depends on your contract or terms when you reduced your hours rather than being a standard HR answer.
I am on 32 hours and that is my contracted weekly hours. Annual leave and public holidays are pro-rata then I have to book off bank holidays if on a working day. If I work extra hours they will be paid and considered as overtime.

Is it considered overtime. Overtime payments don’t usually accrue leave or pension contributions etc.

Yes, your holdiay entitlement has to be calculated using overtime, unless it is genuinely infrequent and unplanned.

The spirit of it is you get holiday based on a weeks normal work, so on the 20 weeks you should get the full allowance, more if you work more than the extra 8 hours.

Holidays are calculated from your hours of work – so yes you get pro rata for every hour you work. Simple as.

This is really a case of what’s in your contract. Are you paid hourly or salary? Working time Exception etc?

Nope – its a legal entitlement. contract is irrelevant unless it specifies more than the legal minimum of 4 weeks plus 8PH