Section 135 Potential lost revenue: normal ruleI1

an inaccuracy in a document (including an inaccuracy attributable to a supply of false information or withholding of information), or

a failure to notify an under-assessment,

an amount payable to WRA having been erroneously paid by way of repayment of WRA-collected tax, F3...

an amount which would have been repayable by WRA had the inaccuracy or under-assessment not been corrected, F4and

an amount which WRA would have been required to set off against a person’s liability to tax, or to pay to a person, had the inaccuracy or under-assessment not been corrected.