SolvedTCTM02460 | Entitlement: WTC entitlement - Qualifying remunerative work
From HM Revenue & Customs · Tax Credits Technical Manual
Unpaid leave
A period of unpaid leave lasting not more than 4 weeks, which is not part of a series of periods spent on unpaid leave, and which does not combine with other factors to reduce normal working hours will not, in its self, affect normal working hours.