ukmercenary

Hi Hope someone can help or point me in right direction. My accountant complete my 2022/23 tax return. **These figures are made up** They calculate my tax to be £4000 before the 1st payment on account of £2000 So I assumed I should have had to pay £6000 by the 31st Jan 2024 However if I look on the HMRC website it say's I only paid £3977.1 It looks like I didn't have to pay the first payment on account, why would this be?, even still I would have expected the £4000 would reconcile with HMRC instead it is £22.9 difference. Not a massive difference but I wondered why?