Tax Collection and Management (Wales) Act 2016 section 135

Potential lost revenue: normal rule

Section 135 defines how to calculate the "potential lost revenue" when there has been an inaccuracy in a tax document or a failure to notify an under-assessment of Welsh devolved taxes.

• Potential lost revenue is the additional tax that becomes payable once an inaccuracy or under-assessment is corrected.
• It includes any amount already erroneously repaid to the taxpayer by the Welsh Revenue Authority (WRA) that must now be paid back.
• It also covers any amount that WRA would have repaid to the taxpayer had the error not been discovered and corrected.
• It further includes any amount that WRA would have been required to set off against a person's tax liability, or to pay to a person, had the inaccuracy or under-assessment remained uncorrected.