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HMRC internal manual

COTAX Manual

Repayments / reallocations: non automatic repayments: repayment interest (Action Guide)

To calculate repayment interest manually, consider steps 1 - 4 below.

1. Determine the CTSA material date (Word 61KB).
2. Determine the date on which the repayment will be issued.
3. Use function RINT (Repayment Interest Calculation) to make the calculation by entering:
  * the day after the material date
  * the date on which repayment will be issued
  * the amount of the repayment.
4. Add the repayment interest to the repayment that you make or use function DSET (District Set-Off) code 50881 to enter the amount of repayment interest on to the COTAX record.