133Penalty for failure to notify under-assessment or under-determination
(1)A person is liable to a penalty where—
(a)a WRA assessment understates the person’s liability to a devolved tax, and
(b)the person has failed to take reasonable steps to notify WRA, within the period of 30 days beginning with the day on which the notice of assessment is issued, that it is an under-assessment.
(2)In deciding what steps (if any) were reasonable, WRA must consider whether the person knew, or should have known, about the under-assessment.
(3)The penalty payable under this section is 30% of the potential lost revenue.
(4)In this section—
(a)“WRA assessment” includes a determination made by WRA under section 52, and
(b)accordingly, references in this Chapter to an under-assessment include references to an under-determination.