Discrepancy between P60 and self-assessment calculation

Dear HMRC customer forum, The self-assessment page calculates that the tax I should pay on my main income (through employment) is £4,104.40, but the tax that was actually deducted at the source by my employer (as shown on my P60) is £4,102.60. I do not understand where this small difference could come from and would be grateful for your help. Best wishes

Hi ,
 

To allow us to explain this difference, we would need to access your record -  contact us by webchat or phone via https: Income Tax: general enquiries to allow us to do this . Thank you .