Why might I pay more tax than my colleague on the same salary?

Even though employees may be on the same salary/hourly rate the amount of tax they pay each period is dependant on the following factors being taking into account.

The previous gross and tax figures on their P45s will be different.

Their tax credits and cut off point may be different. Tax credits and cut off points are issued by the revenue based on an individual’s own personal circumstances which will vary between employees.

They may have worked more hours in the previous periods or even in the current period than their colleagues.