216.Subsection (1) provides that where a person becomes liable for a penalty due to a failure to make a return or pay tax, Revenue Scotland must assess the penalty, notify the person that a penalty has been incurred, and state in the notice the period or transaction against which the penalty is assessed. Subsection (2) provides that the penalty must be paid within 30 days of Revenue Scotland issuing the penalty notification. Subsection (3) provides that the assessment of the penalty is to be treated for enforcement purposes as an assessment of tax and may be combined with an existing assessment to tax. Subsections (4) and (5) make provision for a supplementary and replacement assessments to be made in respect of a penalty applied under sections 159 to 167 and 168 to 173 respectively if the penalty was calculated in reference to the amount of tax the person was liable to pay or failed to pay and it subsequently becomes clear that this amount was an over or underestimate.