The Social Security and Child Support (Decisions and Appeals) Regulations 1999

[F14.  A superseding decision shall take effect from the day the change of circumstances occurs or is expected to occur if—E+W+S

(a) the person ceases to be or becomes a prisoner, and for this purpose “prisoner” has the same meaning as in regulation 1(2) of the State Pension Credit Regulations ; or

(b)whilst entitled to state pension credit a claimant is awarded another social security benefit and in consequence of that award his benefit week changes or is expected to change.]