Last updated 25 October 2026

What is the difference between an advance and an arrears stage payment self build mortgage?

Short answer

With an arrears stage payment mortgage, the lender releases money after a build stage is finished and a surveyor has valued it, so you have to pay for that stage yourself first. With an advance stage payment mortgage, money is released at the start of a stage, so it arrives when the bills do, though advance products usually cost a bit more (The Self Build Guide). Which suits you depends mostly on how much cash you can put in up front and how you’re building. This isn’t financial advice: talk to a specialist self build mortgage broker.

How each one works

A self build mortgage doesn’t hand you the whole loan on day one. It’s released in stages as the house goes up, typically something like groundworks, walls to wall plate, roof on and watertight, first and second fix, and completion. Build It lists stages along those lines and notes that cash is released once inspections confirm the work so far is satisfactory (Build It, Mike Hardwick).

Arrears. The lender pays out once a stage is complete and has been valued. You pay the builder or suppliers, the valuer visits, then the money comes. The Self Build Guide points out that this can strain cash flow, so you may need a cash reserve or a bridging loan to cover the gap, and each stage inspection carries a fee (The Self Build Guide).

Advance. The lender releases money at the start of a stage, so you’re not funding the work out of your own pocket while you wait for a valuation. Lenders carry more risk this way, so expect higher costs or an extra fee (The Self Build Guide).

An illustrative example

This example is illustrative only. The numbers are round and made up to show the cash flow difference. They are not any lender’s terms.

Say a stage costs £50,000 and the lender has agreed to release £50,000 for it.

	Arrears	Advance
Start of stage	You pay £50,000 from your own funds as invoices arrive	Lender releases £50,000; you pay invoices from it
End of stage	Valuer inspects; lender releases £50,000 back to you	Valuer inspects before the next release
Cash you need in hand to get through the stage	Around £50,000, plus a cushion if the valuation is late or lower than expected	Much less, as long as the release arrives on time

Now add an off-site system such as a timber frame. Build It notes that frame and system packages tend to need a significant deposit up front, with the balance due once the structure is up (Build It, Mike Hardwick). If that deposit were, say, £30,000 before anything had been built on site, an arrears mortgage would have nothing to value yet, so the whole deposit would come from you. BuildLoan makes the same point: advance payments matter most when you must pay for materials or a manufactured system before delivery (Legal & General / BuildLoan, Oct 2026).

Who each one tends to suit

Arrears can suit you if you have savings or equity you can use to fund each stage before it’s paid back, your build method spreads costs fairly evenly (traditional masonry often does, per Build It), and you want the lower cost that usually comes with arrears products.

Advance can suit you if you have limited cash after buying the plot, you’re using a timber frame, SIPs or another system with big early deposits, or you’d otherwise need bridging finance to cover the gaps.

Either way, the gap between paying out and getting paid back is the thing to plan for. A late valuation, a stage that runs over, or a valuer who values the work lower than you paid can all leave you short for a few weeks.

Questions to ask a broker

Around 20 lenders typically support self build and custom build projects in the UK (Legal & General / BuildLoan, Oct 2026), and their terms differ a lot. A specialist self build mortgage broker will know them. Useful questions:

Is the release in advance or arrears, and is that the same for every stage?
How many stages are there, and what has to be finished for each one?
Is each release a fixed amount, or based on the valuer’s view of the value added?
What does each valuation cost and how quickly is money released after it?
Can a release cover a deposit for a frame or system before it’s delivered?
How is contingency treated, and can I get at it without waiting for the next release?
What happens if a stage costs more than planned?
What are the fees and rates for advance compared with arrears?

How Self Build Budget helps

You can set your budget up by UK build stage and record every payment against it, so you can see how much you’ll need to fund before each release. On Professional (£20 a month) the 26-week cash-flow forecast shows money going out and funding drawdowns coming in, week by week, so a gap shows up before it happens. You can also give your broker read-only viewer access. See how the method works and pricing.

Questions people also ask

Is an arrears mortgage cheaper? Usually, yes. The Self Build Guide says advance products are usually a bit more expensive because the lender carries more risk. Compare the total cost, including valuation fees and any bridging you’d need, not just the rate.

Do I need a deposit for a self build mortgage? Generally yes. The Self Build Guide says most lenders offer loan-to-value of about 75%, with some going up to 85%. A broker can tell you what’s available now.

What if the valuer values a stage at less than I paid? The release may be lower than you expected, and you’d cover the difference until a later stage. This is one reason to keep a cash buffer on top of your contingency.

Can I switch from arrears to advance part way through? That depends entirely on the lender. Ask before you commit.

Is this financial advice? No. It’s general information from two self builders. Speak to a specialist self build mortgage broker before choosing a product.

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