Their set-off clause reaches into our other contracts

Somewhere in the conditions sits a set-off clause drafted wide: not just deductions arising under this contract, but sums the other side says are due under any contract between you. It sat in the boilerplate, it read like legal furniture, and it got signed. From that day, a problem on one job stopped being a problem on one job.

The width is the point. A snagging argument on a finished project can surface as a deduction from this month's payment here, where the work is clean. Claimed sums, not proven ones, can be pushed through the clause, and the pressure lands on whichever of your contracts has money moving. Your true exposure with that counterparty is the whole trading relationship, and it needs managing as one account, not job by job.

There are still rules. On contracts the Construction Act covers, a deduction generally has to be operated through the payment machinery of the contract it is taken from: valid notices, served in time, stating the sum and the basis. A wide clause does not excuse a missing Pay Less Notice, and deductions that skipped the machinery can be tested. But the durable answer is knowing the clause's reach before pricing the next order with the same counterparty, and negotiating it narrower where you can.