VDIM5050 - Calculation of interest: Setting the calculation date

This guidance deals with interest matters in respect of prescribed accounting periods starting on or before 31 December 2022. Interest matters with effect from 01 January 2023 are dealt with under Finance Act 2009.

Please see Compliance Handbook page CH140000 onwards to find the new interest rules guidance.

The calculation date is the date the tax assessment is made. It is most important that the correct date is entered in red on the front of the VAT 641/642 input document.

This is because the computer automatically calculates the interest due on any interest liable tax amount up to the day before the calculation date of that assessment.

If you do not specify a date, the computer will default to the processing date of the VAT641/642 which may result in too much interest being charged. This could happen if there has been undue delay in processing the VAT641/642 where no calculation date has been specified.

You should be aware that any undue delay could lead to complaints or criticism from taxpayers. If the calculation date is too early not enough interest will be charged.

It is only possible to specify the calculation date at the time you input the VAT 641/642. Once it has been input it will not be possible to amend the calculation date. In such cases it may be necessary to adjust the period the tax amount is liable to interest using the VAT 663 procedures, see VDIM6000. Alternatively an amended assessment may be appropriate.