You cannot get income-related ESA if you or your partner are in ‘remunerative work’, which is work done for payment or in expectation of payment. You are not entitled to income-related ESA if you, the claimant, do any such work (except in some limited circumstances – see Chapter 35(3)). If you have a partner, you are not entitled to income-related ESA if they work for 24 hours or more a week, unless one of the exceptions listed in Chapter 21(3) applies to them (the rules that apply to income support also apply to income-related ESA). If one of these exceptions does apply, earnings are taken into account in the usual way (see Chapter 24(4) -(6)).
ESA Regs , regs 41(1) & 42(1)