Published 2026-07-19 · Contractor Mortgage Guide · Written and reviewed by Phillip Wakeling-Smith (CeMAP)

Sole trader mortgages: how net-profit assessment really works

Q: Is a sole trader mortgage harder than an employed one?

The products and rates are the same — the evidencing is heavier and the assessable figure is often smaller than you feel you earn, because it's post-expenses profit. Preparation (early filing, tidy statements, matching documents) closes most of the gap.

Quick answer: Sole traders are assessed on net profit — the taxable profit on your Self Assessment, evidenced by SA302 tax calculations plus tax year overviews. Most lenders want two years and use the average, unless the latest year is lower — then they use that. A meaningful minority accept one year's trading, and CIS subcontractors get a special exception at some lenders that can transform the numbers. The whole game is which figure a lender uses and how fresh your paperwork is.

What lenders count (and don't)

Your assessable income is the net profit you declared to HMRC — after expenses, before tax. Which means:

Every expense you claim reduces your mortgage capacity. The van, the tools, the use-of-home claim — all legitimately shrink taxable profit, and taxable profit is the mortgage number. Aggressive expensing is a tax strategy with a borrowing cost.
Turnover is irrelevant. A £90k-turnover trade with £30k profit is a £30k applicant.
Two years averaged is the default; a lower latest year usually replaces the average (lenders won't average up past a decline). A rising trend helps at lenders that take the latest year outright.

The paperwork that decides the case

SA302s (tax calculations) for the years required — generated after your return is filed and processed. The timing trap: file in January and there's a window where the newest year effectively doesn't exist for mortgage purposes. If a purchase is coming, file early — a April/May-filed return gives you a current-year SA302 all year.
Tax year overviews — must match the SA302s.
Business bank statements — increasingly used to sanity-check that declared profit resembles real cashflow.
Accountant's certificate at some lenders (an accountant isn't mandatory for sole traders, but having one widens your lender pool).

The CIS exception — the big one for construction

If you're a CIS subcontractor, some lenders skip net-profit assessment entirely and work from your gross CIS income (the pre-deduction figure on your CIS statements/payslips) — usually with 6–12 months' statements instead of two years' accounts. Because gross CIS income is before both the 20% deduction and your expenses, the difference versus a net-profit assessment can be enormous. If that's you, start with the dedicated CIS contractor mortgage guide and the CIS mortgage calculator.

Only one year's trading?

Options exist but the pool shrinks: some lenders accept one full year (sometimes with a strong same-trade employment history before it — the ex-employee-turned-contractor case reads better than a cold start). See the first-time contractor guide for how lenders read a short track record, and the contract timeline checker for whether your history passes specific lenders' rules.

Sole trader vs Ltd: does structure change borrowing?

Sometimes, substantially. A sole trader is assessed on net profit, full stop. Incorporate, and the routes multiply: salary+dividends, salary+retained net profit, or — for day-rate contractors — contract-rate annualisation, which frequently produces the biggest figure of all. Never incorporate for a mortgage without tax advice, but if you're incorporating anyway, the mortgage assessment is one more input to timing.

FAQ

How many years of accounts does a sole trader need for a mortgage?

Two years of SA302s is the standard ask, averaged (or the lower latest year). A worthwhile minority of lenders accept one year, especially with prior employment in the same trade.

Is a sole trader mortgage harder than an employed one?

The products and rates are the same — the evidencing is heavier and the assessable figure is often smaller than you feel you earn, because it's post-expenses profit. Preparation (early filing, tidy statements, matching documents) closes most of the gap.

My profits dipped last year — am I stuck?

Not stuck, but constrained: most lenders will assess on the lower year. Options: lenders that weight the latest year less rigidly, waiting for a stronger filed year, or — if the dip has a documentable one-off cause — a lender that takes explanations. This is a criteria-shopping problem.

Can I count grants, side income or rental income on top?

Regular, evidenceable additional income can count at many lenders (with haircuts); one-off grants generally don't. Each stream is a lender-by-lender question — bring the paperwork and check before applying.