Assessment of tax and interest: Commissioner must calculate interest from default and include it in notices and recovery certificates. The Commissioner must record default tax assessments in Form DVAT-24 and penalty assessments in Form DVAT-24A and serve them as prescribed; calculate interest from the date of default for the period the dealer remains in default and include that interest in the Form DVAT-24 notice; and compute interest up to the date the recovery certificate is signed, indicating that amount separately in the recovery certificate, where the recovery certificate date means the signing date by the appropriate authority.