IHTM30401 | Adjustment of tax paid: underpayments
From HM Revenue & Customs · Inheritance Tax Manual
As a general rule, if too little tax has been paid, the additional tax is payable with interest. This is so even if the tax paid was that stated in a Notice of Determination (NOD) () under . This general rule may be restricted or excluded by any of the following
the instructions on reopening IHT liabilities ()
the instructions on reconsideration of value ()
where there is a change of view of the law or practice ()
lapse of time ()
a clearance certificate () has been issued.
Where a transfer is reported after tax on a subsequent transfer has been settled, you need to consider .