He will pay when the job is finished. Is that allowed?

Somewhere around the first big materials bill, the client mentions his rule: he pays on completion, that is how he has always done it. Four months of wages and merchant accounts, funded by you. Can he?

The right the Act gives you

Section 109 of the Construction Act: a party to a construction contract is entitled to payment by instalments or stage payments, unless the contract specifies, or the parties estimate, that the work will last less than 45 days. On anything longer, staged payment is the statutory default position, not a favour you negotiate.

And where the contract is silent about amounts and intervals, the Act does not leave a hole: the Scheme for Construction Contracts is read in (section 110(3)), and the Scheme provides periodic payments on regular relevant periods. A client cannot beat that by simply refusing to discuss it.

The honest limit, before you quote this page at anyone

Section 109 also says the parties are free to agree the amounts and intervals. So the answer splits cleanly:

• If the signed contract genuinely says one payment on completion, you largely agreed your way out of instalments, and the argument now is a bad one to have started. The lesson belongs to the next tender, not this fight.
• If the contract is silent, or he is announcing the rule mid-job, the Act and the Scheme are on your side: you are entitled to staged payments, and his preference is not a contract term.

What to do this week

1. Read what you signed, specifically anything about payment timing. Silent contract on a 45-day-plus job: write one letter citing section 109 and proposing a monthly valuation date, and let the machinery in the payment timetable do the rest.

2. If you did sign completion-only, contain the damage: keep the deposit and materials funding honest, and watch your exposure like the cash flow risk it is.

3. On every future quote, write the stages in yourself. Monthly valuations, or payments against named stages. It is one paragraph, and it means never needing this page again.

On a job for someone living in the house

Section 109 and the Scheme do not apply to a contract with a residential occupier (section 106), so on the domestic extension there is no statutory right to instalments at all. Your own quote is the only place your stage payments can come from, which makes that one paragraph above not good practice but the entire mechanism. A reasonable stage schedule in a consumer contract is exactly the kind of sensible term that stands.

Where the information stops

Whether a particular clause really does displace instalments, and whether your job is caught by the 45-day line, can both turn on drafting. If the exposure is months of your money, have a construction solicitor read the payment clause before you rely on either answer.