SolvedCH157300 | Penalties for Failure to Pay on Time: Penalty assessments: Enforcement of a penalty
From HM Revenue & Customs · Compliance Handbook
A penalty for failing to pay on time must be paid within 30 days. The 30-day period begins on the date the penalty assessment is issued.
A penalty assessment
may be enforced as if it were an assessment of tax,
is treated, for procedural purposes, in the same way as an assessment of tax, except where there are specific rules, such as time limits, see CH157200, and
may be combined with an assessment of tax.