CH153300 | Penalties for Failure to Pay on Time: Rules for specific taxes: Construction Industry Scheme (CIS): Penalties: Failure to pay all or part of amounts due - further penalties

From HM Revenue & Customs · Compliance Handbook

The second part of the penalty charge for the tax year consists of two 5% penalties:

5% of the deductions on account of tax remaining unpaid 6 months after the penalty date, and
5% of the deductions on account of tax remaining unpaid 12 months after the penalty date.

The penalty date is the day after the due date.

Unlike the default penalty, the further penalties do apply to the first failure in a tax year.

Note that you have a further penalty even if there is no default penalty. This would occur where the first failure remains unpaid for 6 months.

See the example at CH153400.