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HMRC internal manual

COTAX Manual

Interest: how interest is calculated: repayment interest

Repayment interest is automatically calculated when either a repayment or a reallocation is made and:

  • the due date (Word 49KB) has passed
  • the repayment or reallocation is being made after that date
  • a self assessment has been recorded.

Repayment interest is not calculated automatically where a repayable sum is reallocated to OAS, the due date has passed and a self assessment has not been recorded.

COM125060 gives guidance for these circumstances.

Repayment interest is calculated from the later of the day after the normal due date or the date the payment was made, to the date the repayment or reallocation is being made. See CTSA Material dates (Word 108KB) for full details.

You can view repayment interest in function VPPD (View Payments and Postings Details) in the postings screen. The posting type RIN identifies repayment interest. You can view how repayment interest has been calculated by selecting this posting.


  • COM80011 for a list of forms relevant to this subject
  • COM80012 for a list of functions to use in particular situations
  • COM80013 for legislation applying to this subject.