If you do the calculation in accordance with the guidance you start with establishing whether the employee is on a fixed income or a variable income. Then assess whether there had been an RTI submission for a full pay period or only a part pay period. If a part pay period and they are on a fixed income you use as a basis the amount they would have been paid for a full pay period. This has to relate to the amount actually paid. So if they are paid monthly and were only employed for 2 weeks you cannot state that they would have been paid 5 times the amount they were paid. If a part pay period and variable income you take the amount paid and the number of calendar days from the date they were declared employed and the end of the pay period (say 14, for example. Divide the amount paid by the number of calendar days to get the daily pay rate and apply that daily rate 880% to the calendar days they are furloughed. HMRC will look at all RTI returns to assess whether the claim is honest.