Plan for 25–35% of the purchase price in cash, once fees are counted. That's the blunt answer. Most lenders cap residential bridges around 75% loan-to-value, and because the arrangement fee and rolled-up interest usually come out of the gross loan, the day-one advance lands short of the headline. On a £400,000 purchase, a 75% gross facility delivers roughly £262,000 net — the rest is yours to find.
Where the deposit can come from
Cash savings, obviously. Equity released from another property, commonly. Directors' loans into the SPV, gifted deposits, sale proceeds still in a solicitor's client account — all workable, provided the source can be evidenced for anti-money-laundering checks. Lenders care less about where the money sits than whether its history is clean and provable. A deposit that can't be traced is a deposit that doesn't exist, as far as underwriting is concerned.
Additional security instead of cash
This is the lever most first-time bridgers don't know exists. Offer a second property with decent equity alongside the one you're buying — a charge over both — and the lender measures their exposure across the combined value. Structured this way, funding 100% of the purchase price is routinely achievable, because the blended loan-to-value still sits inside their rules. Portfolio landlords use this constantly: the unencumbered flat bought in 2009 goes to work as collateral, and no savings account gets raided.
The trade-offs deserve saying plainly. Both properties are now on the line, redemption needs both charges released, and some lenders charge a little more for cross-collateralised deals because the paperwork doubles. Worth it when cash is deployed elsewhere; not a free lunch.
What doesn't count
Vendor "deposits" that never actually change hands, unsecured borrowing dressed up as savings, and deposits arriving from third parties who aren't giving a documented gift — each of these has killed more completions than valuations have. If your deposit needs a story longer than two sentences, tell your broker before the lender finds it in the bank statements.
The cleanest deals we see put the equity story on one page: what's going in, where it's from, with the evidence stapled behind it. Underwriters reward borrowers who make the money easy to follow.