If the amount of costs payable under an order for costs proceeds to a detailed assessment, the final costs certificate issued will record the date of entitlement to interest and the effect of any rulings which the court has made as to interest. Where a bill of costs covers costs payable under an order or orders in respect of which the receiving party wishes to claim interest from different dates, the bill should be divided into separate parts so as to enable such interest to be calculated. If not so divided the date of entitlement to interest recorded in the certificate will be the latest of the relevant dates.

Only in an exceptional case (e.g. where enforcement proceedings on a final costs certificate are to be taken abroad) will a final costs certificate record the amount of interest accrued up to the date of the certificate and/or the daily rate of interest accruing thereafter. In order to obtain such a certificate the receiving party should apply, on notice to the paying party, justifying the rate of interest claimed and, where payments on account have been made, explaining the effect which such payments have had on the calculation of interest.

In respect of costs payable to a solicitor by a client or former client the final costs certificate will record neither the date of entitlement to any interest nor the amount of any interest accrued or accruing.

Extract from the Senior Courts Costs Office Guide 2018