I have not been able to find an answer online, so suppose that 'accounting principles' will come to bear.
Employers pay out the wages, then get a refund a little later from HMRC - that means that payroll costs will definitely belong to one accounting period, but the refund may arrive in the next. Should we provide for the money that is expected in, or is JRSA taxed on a Receipts basis?
I am conscious that we are not to net the JRSA off against salaries but must show it as a separate item of income. It makes me suppose that HMRC may use 'Big Data' to select cases for enquiry, so would want to stick to the rules as closely as possible.