Are you the employer or a book-keeper/payroll person etc?
None of us here (as far as I am aware) are employment law experts. I have a little knowledge but not enough for me to be comfortable saying any more than to seek advice depending on what their contract says with regards to payment periods. Personally I'd take the view its too much hassle to go round pro-rataing for one day. Yes technically speaking if a month runs from 1st - 30th/31st then they won't yet have accrued the day holiday to cover the bank holiday 1st (assuming thats why they started on 2nd Jan.) But if it was me I woud be saying to my boss is it really worth it and what impression does it give the new employee?
-- Edited by pictures on Friday 26th of January 2018 03:34:15 PM
If the contract states he starts actually on the 2nd of January then I would check with the client/boss, but I would say that he hasn't got paid for the 1st Jan. Also he wouldn't have accrued enough holiday to actually get paid for bank holiday. It really is whatever date is on his contract. Like for instance if his contract stated he started on the 3rd of January then you wouldn't be paying the 1st or the 2nd.
This is just my take on it as I do quite a bit of payroll, but really need to check with your boss and look at the contract.