Can I claim interest on late payment?

Usually, yes. Most business to business construction debts fall under the Late Payment of Commercial Debts (Interest) Act 1998, a statute that, where it applies, automatically adds interest at 8% above the Bank of England base rate on money paid late, plus a small fixed sum for each debt and, where your reasonable costs of chasing the money exceed that sum, the extra too. Your contract can set its own interest term instead, but only if it is a genuine, substantial remedy; a token rate set deliberately low to make paying late cheap can be struck out, letting the statutory 8% rate back in. Interest is rarely the reason to run a dispute on its own, but claiming it in an adjudication, the fast dispute process, or in negotiating the final account, the settling up at the end of the job, is routine, and puts a real price on the other side's delay.

A joinery subcontractor is paid a £50,000 invoice three months late by a commercial contractor. Because this is a business to business construction debt, the 1998 Act lets it add interest at 8% over base rate across those three months, plus a fixed sum for the debt and, if chasing it cost more than that sum in reasonable expense, the shortfall too. If the subcontract instead set interest at a token half a percent a year, designed to make late payment painless for the contractor, that term could be struck out and the 8% statutory rate would apply anyway. The subcontractor is unlikely to fight purely over the interest, but adding it to the sum in dispute when the account is negotiated or adjudicated puts a genuine cost on the delay.