Automatic arrears calculation

Suppose a court order for maintenance against an employee specifies that £30 should be deducted from their earnings monthly. Their protected earnings are £1,000 and in this particular month their attachable arrestable earnings were £1,010. The payroll will calculate as follows:

Protected earnings: £1,000

Court order £30

Arrestable Earnings £1,010

Deduction £10

Arrears of order £20

To be deducted next month £50