There is no upper age limit for claiming carer’s allowance or, in Scotland, carer support payment (CSP) but you must meet the usual qualifying conditions (see Chapter 8(2) and Box C.1 in Chapter 8).

If you are entitled to carer’s allowance or CSP after pension age, you may not appear to be better off due to the overlapping benefits rule. Carer’s allowance and CSP overlap with state pension, so once you reach pension age and draw your pension, carer’s allowance or CSP can only continue to be paid if your state pension is less than the rate of carer’s allowance. However, even if your carer’s allowance or CSP is overlapped, it is often still worth claiming because it can increase your income from pension credit through the ‘additional amount for carers’ (see Chapter 45(3)) or from housing benefit through the ‘carer premium’ (see Chapter 23(6)).
OB Regs, reg 4(1)&(5)