IHTM31686 | Assessing: offset repayments: non-payment of calculation
From HM Revenue & Customs · Inheritance Tax Manual
Sect 6 procedure
Sometimes you may need to withdraw a calculation that has had a repayment set off applied - perhaps because you are told about further amendments. You can withdraw the calculation and raise a new one, using the set off repayment as a deposit. Use the warrant number as the deposit number.