Is it a New Starter ? Did you enter the historical pay values as per the P45? Other things to check would be the Tax Code (ensure no transposition errors, does it look 'reasonable'.) You could query this with the employee if there's anything that looks wrong. 

It's worth querying but it can happen if it's a new starter, as even though they earn enough monthly to be paying tax, the PAYE is cumulative (unlike NIC). This means that if there have not been sufficient earnings earlier in the year, until their total income for the year exceeds £12,570 then they will not have any deductions up until after that point.

Hi William,

Thank you for using Community hub.

Stuart is right in his reply to you, sometimes the employee hasn't earned enough in the year to pay tax when they first start working for you.

Figures on the P45 you enter into payroll  will determine when the employee will start to pay tax.

If the employee didn't bring you a P45, you use the P46 declaration instead.

Please read the article in the link below, from the Previous Tax Details section.

Create and edit employee records

The P46 declaration will assign the employee the correct tax code for their particular circumstances.

It will also determine if they need to be entered on a week1/month 1 basis.

Kind regards,

Nigel

Sage UKI