How to Pay a Builder Safely: Deposits, Stage Payments and Milestone Protection

How you pay a builder matters almost as much as who you hire. Get it right and your money stays close to the work, the job keeps moving, and both sides know exactly where they stand. Get it wrong and you can find yourself hundreds or thousands of pounds ahead of what has actually been built, with all the leverage sitting on the other side of the table. The good news is that paying safely is not complicated. It comes down to a few clear principles that anyone can follow, whether you are having a bathroom refitted or building a two storey extension.

We run DDC Scaffolding and build Complys, so we see payment from both sides. Builders need enough cash flow to buy materials and pay their crew, and homeowners need confidence that their money is buying real progress. A good payment structure serves both, and that balance is what this guide is about. We will cover the golden rule, deposits, stage payments, retentions, which payment methods protect you, how to handle extras and disputes, and how milestone protection brings it all together, finishing with a simple plan you can copy.

The golden rule: never get ahead of the work

If you remember one thing, remember this. Your payments should always trail slightly behind the value of the work completed, never run ahead of it. When your money is behind the work, the builder has every incentive to keep going, because the next payment depends on progress. When your money is ahead of the work, that incentive weakens, and in the worst cases it disappears entirely. Every safe payment structure is really just a way of keeping this rule true from the first day to the last.

This is not about assuming your builder is dishonest. It is about aligning everybody's interests so that finishing the job well is always the easiest and most rewarding thing for the builder to do. A good builder will not object to this, because it is how professional contracts work throughout the industry, and it protects them too by making expectations clear. If a builder pushes hard against ever letting your payments trail the work, that resistance is itself worth thinking about.

Deposits done properly

A deposit is normal and reasonable. Builders often need to secure materials or reserve a slot in their schedule, and a modest deposit shows you are serious. The key word is modest. As a rough guide, a deposit of around 10 to 25 percent of the job is common for smaller projects, and it should have a clear purpose you both understand, such as ordering specific materials or holding a start date. On a very large project the percentage will usually be smaller, because a quarter of a major build would be a very large sum to have at risk before anyone lifts a tool.

Be very cautious about any request for a large deposit, say half the total or more, before work begins. There are occasional legitimate reasons, such as a costly bespoke item that must be ordered and paid for up front, for example made to measure windows or a special staircase, but even then the money should be tied to that specific purchase and evidenced with an order or invoice from the supplier. A blanket demand for a big deposit with no clear reason is one of the most common features of jobs that go wrong. If you do pay a sizeable deposit, paying it on a credit card gives you Section 75 protection for amounts between 100 and 30,000 pounds, which is a valuable safety net if the builder later fails to deliver.

Understanding a builder's cash flow

It helps to understand why builders ask for money in the way they do, because it lets you tell a reasonable request from an unreasonable one. A builder carries real costs from day one. They buy materials, hire plant, pay wages and cover their own overheads, often before you have paid anything. A fair payment schedule is one that keeps them from having to fund your entire job out of their own pocket while still keeping your money close to the work. That is why paying only at the very end is not actually fair or realistic, and why a builder who wants regular stage payments is usually just running a sensible business.

The problem is not staged payment, it is payment that runs too far ahead of progress or lands in one big lump at the start. Once you see it this way, the conversation with your builder becomes easier. You are not refusing to pay, you are agreeing a rhythm of payments that matches the rhythm of the work, which a professional will recognise and respect.

Stage payments that match progress

For anything beyond a small job, the safest approach is to break the total into stage payments, each released when a defined chunk of work is finished. The stages should be tied to visible, checkable milestones rather than dates on a calendar. A payment due on the fifteenth of the month rewards the passage of time, whereas a payment due when the roof is watertight rewards actual progress, and that difference is the whole point.

On an extension, for example, you might structure payments around a set of natural milestones. A deposit to order materials and secure the start. A payment when the foundations are dug and poured. A payment when the walls reach damp proof course level. A payment when the walls are up and the roof structure is on. A payment when the extension is watertight, with roof, windows and doors in. A payment after first fix of plumbing and electrics. A payment after plastering. And a final payment on completion, once snags are done. Each payment is earned by reaching a real point in the build that you can see and verify. Agree the stages and the amount attached to each in writing before work starts, so there is never any confusion later about what has been earned.

A sample payment plan you can adapt

To make this concrete, imagine a job priced at 40,000 pounds. A safe structure might look like this. A deposit of 4,000 pounds, which is 10 percent, paid by credit card to order materials and hold the start date. Then a series of stage payments of roughly 6,000 to 7,000 pounds each, released as the foundations, the walls, the watertight shell, the first fix and the plastering are each completed and checked. That leaves a final sum of around 4,000 pounds, which is 10 percent, held until the job is finished and any snags are put right. The exact figures will vary with the job, but the shape is what matters. A small deposit, several payments tied to real milestones, and a meaningful sum retained until the very end.

Notice how at no point are you far ahead of the work. If the builder walked off after the walls were up, you would have paid for roughly what had been built, not for the whole job. That is the protection a good schedule gives you, and it costs nothing beyond a little thought at the planning stage.

Hold a retention on larger jobs

On bigger projects it is common and sensible to hold back a small retention, often around 5 percent, for a period after the work is finished. This covers any snags or defects that only show up once you are living with the finished work, such as a door that drops, a hairline crack as plaster dries, or a leak that only appears after heavy rain. You release the retention after an agreed period, commonly a few weeks to a few months, once you are satisfied everything is right. A reasonable builder will understand this, because it is standard practice throughout the construction industry, and it gives them a clear incentive to come back and finish properly rather than move straight on to the next job.

Which payment methods protect you

The method you use changes how much protection you have if something goes wrong. Credit cards offer the strongest protection through Section 75 for purchases between 100 and 30,000 pounds, making the card provider jointly liable if the work is not done. For that reason, paying at least part of a large job by credit card is a smart move even if you clear the balance immediately, because it buys you that legal backstop at no real cost.

Debit cards and bank transfers are convenient and fine for stage payments once you are confident in the builder, but they carry less built in protection, so they suit money that is closely matched to completed work. Debit card payments may still be recoverable through chargeback if a job is abandoned, but a bank transfer offers little recourse once it has gone. Cash is the weakest option of all, because it leaves no clear trail and no recovery route, and a builder who insists on cash and refuses an invoice is a builder to be wary of. Whatever method you use, always get a proper invoice or receipt for every payment, and keep those records together with your contract. That paper trail is what turns a dispute from your word against theirs into a documented case.

Handling extras, variations and VAT

Almost every project changes a little along the way. You decide on a nicer tile, an unexpected problem is uncovered when a floor comes up, or you add a job while the builder is on site. These changes are called variations, and they are the source of a huge share of payment disputes, because they are so often agreed casually and then argued about later. The fix is simple. Agree every extra in writing before the work is done, with its own price, even if it is only a quick text confirming the cost. That way the final bill holds no surprises, and you keep control of the total rather than watching it drift upward one vague extra at a time.

Be clear about VAT too. Ask whether quoted prices include VAT, because a 20 percent difference between an inclusive and an exclusive quote is easy to miss and can blow a budget. A VAT registered builder should show their VAT number on invoices. Some work on certain properties can qualify for a reduced or zero VAT rate, for example some energy saving measures or work on certain new or converted dwellings, so it is worth asking, but the key thing for your budget is simply to know whether the numbers you have been given include the tax or not.

What to do when you disagree about a stage

Sometimes a builder says a stage is finished and you are not sure it is. Handle this calmly and in writing. Set out specifically what you think is outstanding, refer back to what the contract said that stage would include, and ask for it to be completed before the stage payment is released. Keep paying for what genuinely is done, because withholding money for completed work in a dispute about one item can put you in the wrong. If you cannot agree, many trade schemes offer a dispute resolution or mediation service, and for larger contracts adjudication may be available, which is faster and cheaper than court. The point is to keep the disagreement about facts and the contract, not personalities, and to keep a written record throughout.

Should you ever pay for materials directly?

One question that comes up often is whether you should buy materials yourself rather than pay the builder to supply them. There are arguments both ways. Buying big ticket items directly, such as a kitchen, bathroom suite or expensive tiles, means the money goes straight to the supplier and you own the goods, which can reduce the sum you have at risk with the builder and give you Section 75 protection on those purchases if you use a credit card. It also lets you choose exactly what you want. The downside is that you take on responsibility for ordering the right items, in the right quantities, at the right time, and if something is wrong or delayed, the builder can fairly point out that the hold up was not their doing.

For most people a sensible middle path works well. Let the builder supply the everyday materials, since they know what is needed and can source it efficiently, but consider buying the few costly, personal items yourself and having them delivered to site for the builder to fit. If you do leave materials in the builder's hands, avoid paying large sums up front for goods that have not yet arrived, and where a big materials payment is unavoidable, ask to see the supplier order or invoice so your money is tied to a real purchase rather than a promise.

Milestone protection: the modern way to pay safely

Stage payments are a big step up from a large deposit, but they still rely on you judging whether each stage is genuinely complete, often without the expertise to know for sure. Milestone protection takes the idea further. Instead of simply paying when you think a stage looks done, the builder submits evidence that the stage is complete, that evidence is reviewed, and payment is released only once the stage checks out and you approve it.

This is exactly what Project Guard does inside Complys. At each stage of the work your builder uploads photos and writes a short report on what was done. Our system reviews the photos and the report and explains in plain English whether the work matches what you agreed, flagging anything that looks off or worth a closer look. You see that summary, you approve the stage, and only then does payment move on. It keeps the golden rule true automatically, because money never travels ahead of verified work, and it gives you a plain second opinion at exactly the moment you need one, which is when you are deciding whether to release the next payment.

A simple payment plan you can copy

For a typical home project, a safe structure looks like this. A modest deposit tied to materials or a start date, ideally paid by credit card. A series of stage payments, each released when a defined milestone is reached and checked. A small retention held back on larger jobs for a defined snagging period. Every extra agreed in writing before it is done. A written contract that records all of it, and a proper invoice kept for every payment. Follow that pattern and you keep control of your money from start to finish.

You can find trades whose insurance and paperwork have been verified in the Complys directory, request quotes for free, and read more about milestone protection on the homeowner page. If you want the wider picture on hiring well, our guide on how to avoid rogue builders covers the checks to make before any money changes hands, and our guide on what to do if a builder disappears with your money shows why keeping payments close to the work matters so much.

The bottom line

Paying a builder safely is not about being difficult. It is about keeping your money in step with the work, using a modest and purposeful deposit, releasing the rest in stages tied to real milestones, holding a small retention on bigger jobs, agreeing every extra in writing, and paying by a method that protects you. Do that, keep everything in writing, and the payment side of your project stays firmly under your control from the first day to the last.