Why a single invoice at the end is a risky way to run a project

If you take on a job worth a few thousand pounds and invoice only when the work is finished, you are effectively lending your client money for weeks or months. You pay for materials, subcontractors and your own time up front, then wait for a single payment that may arrive late, in part, or not at all. For a small business, one bad debt on a large job can wipe out the profit from several good ones.

Splitting a project into a deposit plus staged payments changes that picture. You fund each stage from money already collected rather than from your own reserves, you spot problems earlier, and you give the client a series of smaller, easier-to-approve sums instead of one intimidating final bill. It also signals that you run your business professionally, which tends to attract better clients rather than put them off.

Setting the deposit and the stages

On most custom or project-based work, a deposit of 25 to 50 per cent is normal, with the balance divided across two or three further payments. The deposit should do real work: cover materials, booking time in your diary, and give you something to hold if the client disappears.

Choose stages that are easy to verify, ideally tied to something the client can see or sign off:

• Deposit on acceptance – paid before you order materials or start design work.
• Design or specification sign-off – invoiced when the client approves drawings, a written scope or a sample.
• Delivery milestones – for example, first fix complete, frame erected, software in staging, content approved.
• Practical completion – the bulk of the remaining balance when the work is usable, not necessarily perfect.
• Final retention – a small percentage, often 5 to 10 per cent, held for an agreed period to cover snagging.

Avoid vague milestones such as "halfway through". They invite argument. If the client cannot see the trigger, they will query the invoice, and queries cost you time.

Say clearly when each payment becomes due

The single most common cause of late payment is a contract that describes what you will do but never quite says when money is owed. Your terms should state, for each stage, the trigger event and the payment period that follows it — for example, "the deposit is due on acceptance of this quote and is payable before work commences; stage two is due within 14 days of written approval of the design".

Being precise matters legally as well as commercially. Under the Late Payment of Commercial Debts (Interest) Act 1998, business-to-business debts can attract statutory interest and compensation, but the clock runs from an agreed due date. If your terms say nothing, you fall back on default rules and lose the certainty you could have had. For a consumer client, the rules differ, so keep your terms fair, transparent and compliant with consumer law.

It also helps to spell out:

• Whether each payment is a deposit, part payment or full settlement of a stage.
• Whether amounts exclude VAT, and when VAT becomes chargeable.
• What happens if the client delays approval, access or materials — the milestone moves, but your right to be paid for work done does not.
• Your right to suspend work while an invoice is unpaid, and to charge interest on late sums.

Invoicing at each stage without friction

Send the invoice the moment the milestone is reached, not at the end of the month. Attach evidence: photographs, a signed-off checklist, a link to the work, or a short note confirming the trigger has occurred. The easier you make it for the client to approve internally, the faster you get paid.

Raise a proper VAT invoice for each stage if you are VAT registered, showing your VAT number, a sequential invoice number, the date, the amount excluding VAT, the rate and the total. Keep the invoicing descriptions aligned with the wording of the contract, so stage two on the invoice reads like stage two in the agreement.

On longer jobs, consider asking for payment by standing order or bank transfer on a set date for the recurring stages. Anything that removes a decision from the client's to-do list is a small win for your cash flow.

Managing changes, delays and difficult conversations

Variations are where staged payments earn their keep. If the client asks for extra work, price it separately and agree when it will be invoiced, ideally as an additional stage or as an amendment to an existing one. Never absorb variations into the final payment, because that is the payment most likely to be disputed.

When a payment runs late, act early and politely. A short, factual email — referencing the agreed date, the invoice number and the consequence, such as pausing work — is usually enough. Escalate only if the pattern repeats. It is far easier to protect a working relationship at seven days overdue than at ninety.

Finally, review your terms after each significant project. If a stage caused confusion, rename it. If a client held back more than expected, tighten the wording. Deposits and staged payments are not a sign of distrust; they are simply the mechanics that let you deliver good work without carrying the whole risk yourself.