Off-Plan Finance and Currency Risk

Each of these is well understood on its own. What buyers underestimate is that on a long completion they arrive together, and they are correlated — the same macro conditions that move exchange rates also move lending appetite and valuations.

The correlation is what makes this uncomfortable. A sterling shock, a rate shock and a valuation shock are not independent events; the conditions that produce one tend to produce the others. Underwriting each exposure separately and concluding that each is tolerable is not the same as underwriting them together.

The threshold is not a legal one. It comes from the practical fact that a mortgage offer cannot bridge it. Six months is a long offer validity, and even a new-build extension does not reach a year on standard terms — so anything beyond about 24 months from exchange means you will apply for finance in conditions you cannot see from here, at a point when you are already contractually committed.

Off-plan completion dates also move. Contracts are normally drafted around a long-stop date rather than a fixed day, with the developer serving a notice to complete once the building is legally complete and giving you a short window — often ten to fourteen working days — to pay the balance. That structure is reasonable for a developer and awkward for a buyer, because the exact date on which you need the largest sum of money is not fully in your control. If you are relying on a mortgage drawdown and a currency conversion landing in the same fortnight, that window is where things go wrong.

None of this argues against off-plan. It argues for choosing the right off-plan. A unit completing in nine months is a fundamentally different financial instrument from one completing in three years, even in the same building, and it should be underwritten differently.

• Find the long-stop date in the contract, not the marketing date on the brochure.
• Find the completion notice period, and confirm you can fund inside it.
• Ask what happens if the developer misses the long-stop date, and whether you can rescind.
• Ask whether the contract permits assignment before completion, and on what terms — that is your exit if circumstances change.
• Confirm whether the deposit is held as stakeholder or as agent. It matters if the developer fails.

Most new homes in the UK are sold with a structural warranty — NHBC Buildmark is the best known, alongside LABC Warranty, Premier Guarantee and Checkmate. These are usually described in terms of the ten-year structural cover that starts at completion, but for an off-plan buyer the more relevant feature is the insolvency cover that applies before completion, covering the buyer if the builder becomes insolvent and cannot finish the home or refund what has been paid.

That protection is capped, and the cap is the part buyers skip. Under NHBC Buildmark the limit on this section is 10 per cent of the original purchase price, up to a maximum of £100,000 — the lower of the two, not the higher. On a £1.2m London flat with a 20 per cent exchange deposit, that means £240,000 paid over and £100,000 covered. The uncovered £140,000 is, in substance, unsecured credit you have extended to the developer, and it should be assessed as such. Read the policy document for the specific scheme rather than the brochure page, because the schemes differ and their terms have changed over the years.

The exclusions matter too, particularly for investors. Buildmark's insolvency cover requires that you always intended to complete the purchase and occupy the home yourself or let it to tenants; it is excluded where the money was paid as a short-term investment to fund construction in expectation of a return rather than a completed purchase. A staged "investment" deposit into a development-funding structure may therefore sit outside the cover entirely.

There is a timing point that matters even more. Buildmark's insolvency cover runs from exchange of contracts and is evidenced by an insolvency cover certificate that your conveyancer confirms after exchange. Money paid at reservation stage, before exchange, sits outside it. The Consumer Code for Home Builders governs reservation agreements and requires reservation fees to be refunded on cancellation subject to reasonable deductions, but it is a code of conduct, not an insurance policy, and it does not itself protect the contract deposit. Ask in writing which scheme covers your plot, what the cap is in pounds for your price, and from what date cover attaches — and do not release a material sum until your conveyancer confirms the certificate exists.

• Ask which warranty provider covers the specific plot, and get the policy document, not the brochure page.
• Ask for the insolvency-cover cap expressed as a pound figure for your purchase price, and compare it directly to your deposit.
• Ask when cover attaches, and confirm the insolvency cover certificate is in place before releasing funds.
• Ask whether the deposit is held by the developer's solicitor as stakeholder — stakeholder money cannot be released to the developer before completion.
• If the deposit exceeds the cap, treat the excess as unsecured credit extended to the developer, and consider whether the covenant justifies it.
• Check the exclusions against how you actually intend to use the property, particularly if the purchase is structured as an investment rather than a completed sale.

This is worth setting out precisely, because it is frequently described in a way that makes it sound either apocalyptic or negligible, and it is neither. It is arithmetic.

Suppose you exchanged at £1,200,000 with a 10 per cent deposit, planning to borrow 70 per cent. You expected a £840,000 loan and a £360,000 balance, of which £120,000 was already paid. At completion the valuer assesses the flat at £1,100,000. The lender applies 70 per cent to £1,100,000, not to £1,200,000, so the advance is £770,000. You are still contractually bound to pay £1,200,000. Your cash requirement at completion has risen from £240,000 to £310,000 — an extra £70,000, found at short notice.

There is no statistic here worth quoting, because down-valuation frequency varies enormously by market phase, by scheme and by whether the original price was set against comparable evidence or against a developer's forward projection. The point is not that it is likely. The point is that the exposure exists, it is entirely one-directional — a valuation above the contract price gives you nothing — and it can only be absorbed with cash. So the question to answer before exchanging is not whether it will happen, but whether you could complete if it did.

• Ask what the developer's units in the same scheme have actually sold and valued at, not what they are listed at.
• Ask whether the price includes incentives — stamp duty contributions, furniture packs, rent guarantees — because a valuer will strip those out.
• Stress-test your cash position against a valuation 10 per cent below the contract price.
• If that stress test fails, the answer is a smaller purchase or a shorter completion, not a more optimistic assumption.

If completion is more than roughly 24 months away, the only conservative basis for the decision is that you could complete without a mortgage and without a favourable exchange rate. That does not mean you must complete in cash — most buyers will use finance, and that is fine. It means the purchase should not fail if finance is unavailable or expensive on the day.

In practice this is a liquidity test rather than a wealth test. Sterling assets or a committed sterling facility that can cover the balance; a currency plan that fixes at least the bulk of the exposure rather than hoping; a cash buffer sized against a plausible down-valuation; and a completion window you have actually mapped against how long your funds take to move internationally.

Buyers who fail this test have a straightforward alternative, and it is not to abandon off-plan. It is to buy later in the build cycle. The same building at practical-completion stage carries a fraction of the exposure: a mortgage offer can be held to completion, the currency period is weeks rather than years, and the valuation risk is largely resolved. You give up some of the early-stage price advantage. On a long completion, that advantage is what you were being paid to take these risks, and it is worth checking whether it is actually enough.

• Could you complete if no lender would advance on the day? If not, the purchase is not underwritten.
• Could you complete if sterling moved 15 per cent against your income currency? If not, hedge or reduce the purchase.
• Could you complete if the valuation came in 10 per cent light? If not, hold more cash back.
• Do you know how many working days your funds take to reach a UK client account, including compliance checks on source of funds?

This is not a forecast and not a worst case — it is a scaling exercise using rates that actually occurred. On the Bank of England's daily spot series, sterling against the US dollar stood at 1.4211 on 18 May 2021 and at 1.0745 on 28 September 2022: a fall of 24.4 per cent in roughly sixteen months, comfortably inside the window of a long off-plan completion. Applied to a £1,200,000 purchase with a 10 per cent deposit at exchange, the dollar cost of the completion balance alone moves like this.

Rates are the Bank of England 4pm daily spot fix (series XUDLUSS), quoted for illustration only. Sterling briefly traded near $1.03 intraday on 26 September 2022 after the mini-budget, but that is a market print rather than a Bank of England rate, so the more conservative official fix is used here. The arithmetic is simply the balance multiplied by each rate.

Note the direction carefully, because it is symmetric and it is easy to get backwards. A dollar-funded buyer benefits when sterling weakens and is hurt when sterling strengthens. Over a two-year completion, either can happen, and a move of this magnitude is neither rare nor extreme. The point is the size of the number relative to the whole transaction — $374,328 is more than three times the deposit — not the direction of any particular episode.

There are three broad responses to an open currency position on a property purchase. Each has a real cost, and the cost of the third one is simply less visible than the others.

Positions on this page are stated as at August 2026. Warranty terms, lender policies and exchange rates all change; verify against the primary source before relying on any figure.

• NHBC Buildmark — cover and policy documents
• Consumer Code for Home Builders
• Bank of England — daily spot exchange rates database
• FCA Financial Services Register — check any FX provider's permissions
• FCA Handbook, MCOB — mortgage conduct of business rules
• 2025 Mortgage Guarantee Scheme rules — GOV.UK (definition of Value as valuation or price, if lower)
• GOV.UK — buying a new-build home