Definition of set something against in US English:

set something against

phrasal verb

  • Offset something against.

    ‘wives' allowances can henceforth be set against investment income’
    • ‘Well, I switched to a flexible mortgage, because I'm self-employed and I can set my tax against my mortgage until I have to pay my tax bill.’
    • ‘Offset and current account mortgages work by setting your savings against your borrowings.’