If the whole or any portion of a penalty is not paid by the date by which it is required to be paid, the unpaid balance from time to time shall carry interest at the rate for the time being specified in section 17 of the [1838 c. 110.] Judgments Act 1838.

Where an application has been made under section 32(5), the penalty shall not be required to be paid until the application has been determined, withdrawn or otherwise dealt with.

If a portion of a penalty has not been paid by the date required for it, the Commission may, where it considers it appropriate to do so, require so much of the penalty as has not already been paid to be paid immediately.