PAYE50935 | Employer returns: employer starter and leaver forms: employer e-file in-year penalties: in-year penalty cycle

From HM Revenue & Customs · PAYE Manual

In-year penalties are issued 4 times a year, usually in the third week following the end of the tax quarter in which the employer has not filed starter and leaver forms online.

The tax quarters are

Q1 6 April - 5 July

Q2 6 July - 5 October

Q3 6 October - 5 January

Q4 6 January - 5 April