HMO mortgage

HMO mortgages are a specialist part of buy-to-let lending. Fewer lenders offer them than standard buy-to-let loans, and those that do look closely at the room income, the licence and planning position, the layout and the landlord’s experience. Rates, fees and rental cover tests are usually tighter than for a single let, so size the loan against the income each lender will actually count.

Per-room ICR is the foundational difference. A 6-bed HMO at £550 per room generates £3,300 of monthly gross rent: £39,600 annually. After a 10–15% void allowance (HMO turnover is higher than single-let) and bills (£120–180 per room), the lender works on net rent of around £25k–27k. At 5.5% stress on a £165k loan with 145% ICR, required net rent is £13,200 × 1.45 = £19,140: the deal passes. At 7% stress and 170% ICR (specialist HMO lenders’ default for higher-rate landlords) the required figure is £165k × 7% × 1.70 = £19,635: marginal.

Loan-to-value caps are also lower. Mainstream BTL routinely lends to 75% LTV; HMO mortgages typically max out at 70% (sometimes 75% for sub-6-bed standard HMOs with 12+ months of stable income). Large HMOs (7+ rooms), purpose-built blocks, and complex tenure types (leasehold flats above commercial premises) often max at 65%. The cap pushes the deposit requirement higher: a £220k purchase needs a £66k–77k deposit on the mortgage alone, plus SDLT and conversion cash on top.

The bricks-and-mortar vs commercial valuation distinction drives the maximum loan and the refinance strategy. Bricks-and-mortar valuation treats the property as a residential dwelling, typically the original purchase price plus modest improvement uplift. Commercial valuation treats it as an income-producing asset valued on a yield multiple: a 6-bed HMO with £22k net annual income at a 9% yield is worth £245k, at 8% is £275k. Larger HMOs (typically 7+ rooms) with 12+ months of stable income usually qualify for commercial valuation; smaller HMOs revert to bricks-and-mortar. The valuation method controls whether you can pull cash out at refinance or remain locked into your initial deposit.

Day-one refinance after refurbishment is the high-leverage strategy that drives much of the HMO market. Buy a tired single-let property with cash or short-term bridging finance, complete the HMO conversion, then refinance after 6–12 months on commercial valuation. If the converted HMO commercial-values at £320k vs a £220k purchase + £80k conversion = £300k all-in, the borrower can refinance to 70% LTV (£224k loan) and pull £24k of equity back out while retaining the cash-flowing asset. The stress test on the new mortgage uses post-conversion per-room income.

Limited Company HMO mortgages have been the largest growth area since 2020. Ltd company borrowers benefit from full mortgage-interest deductibility and the lower 125% ICR threshold (because Ltd interest is fully deductible vs 20% credit only in personal name under Section 24). The trade-off is a higher product rate (typically 0.4–0.7% premium over personal-name HMO) and higher arrangement fees. For higher-rate taxpayers operating HMO portfolios, the Ltd structure usually wins on post-tax cash flow above £50k of property profit. Use this calculator to test maximum loan in personal-name vs Ltd structure before committing to either.