Week One or Cumulative Basis
CUMULATIVE BASIS
The purpose of the PAYE system is to ensure that an employee’s tax liability is spread out evenly over the year, thus allowing the correct tax liability to be paid in full without causing hardship to the employee.
To ensure that this is achieved, PAYE & USC are normally calculated on a Cumulative Basis. This means when employers calculate the tax liability of an employee, they actually calculate the total tax due from the 1st January to the date on which the payment is being made. The PAYE tax and USC deducted in a particular week is the cumulative amount due from the 1st January to that date, reduced by the amount previously deducted to date.
Any tax credits and/or standard rate cut off point and/or USC cut off point, which are not used in a pay period, can be carried forward to the next period within the tax year. The cumulative basis also ensures that refunds can be made to an employee where the employee’s tax credits and cut off points have been increased.
WEEK 1 BASIS
If the week/month 1 basis applies, neither pay, tax credits, nor the standard rate cut off point nor USC cut off points are accumulated for tax and USC purposes. The pay for each week or month is dealt with separately. The tax credits, standard rate cut off point and USC cut off points for week/month 1 are used each week/month in the calculation of tax and USC due.
PAYE & USC Refunds will not be triggered under a Week 1 / Month 1 basis, as refunds only occur in a cumulative basis.