ar ‧ rears /əˈrɪəz $ əˈrɪrz/ BrE AmE noun [plural]
[ Date: 1400-1500 ; Origin: arrear 'backward, behind' (14-18 centuries) , from Old French arere , from Vulgar Latin ad retro 'to the back' ]
1 . be in arrears if someone is in arrears, or if their payments are in arrears, they are late in paying something that they should pay regularly, such as rent:
Many people are in arrears with their rent.
be four weeks/three months etc in arrears
The rent money is two months in arrears.
fall/get into arrears (=become late with payments)
2 . money that you owe someone because you have not made regular payments at the correct time:
We’ve got 3 months' arrears to pay.
rent/mortgage/tax arrears
He was ordered to pay rent arrears of £550.
3 . paid in arrears British English if your salary is paid in arrears, it is paid at the end of the period you have worked:
a salary paid monthly in arrears