As a self-employed driver, claiming your allowable expenses is exactly what you should do at tax time: it lowers your taxable profit and your tax bill. But there is a trade-off that catches a lot of drivers out when they come to buy a home or remortgage. The same expense claims that cut your tax also cut the profit figure a mortgage lender uses to decide how much you can borrow. The two goals, paying less tax and borrowing more, pull in opposite directions, and it pays to understand that before you apply.
What a lender actually looks at
For an employee, a lender looks at salary. For a self-employed driver, it looks at your net profit, the figure after expenses, not your gross fares. Lenders generally want to see two to three years of accounts or tax calculations, and they typically lend up to around four and a half times your income. The income they use is the profit you declared to HMRC, evidenced by your tax year overview and SA302 tax calculation. MoneyHelper's guidance on how much you can afford to borrow sets out how that affordability assessment works.
Why heavy expense claims work against you here
Every pound of expense you claim reduces your declared profit by a pound. That is good for tax, but a lender reads it as a pound less income. A driver with £40,000 of fares who claims £15,000 of expenses shows a £25,000 profit, and is assessed on £25,000, not £40,000. Which? puts it bluntly in its guide to mortgages for self-employed buyers: if you keep your net profit low to pay less tax, that becomes a sticking point, because to borrow more your net profit needs to be as high as the figures honestly allow.
This is not a reason to stop claiming legitimate expenses, and it is certainly not a reason to invent them. It is a timing and planning issue: the figures you file in the two or three years before a mortgage application are the figures the lender will judge you on.
How to plan around the trade-off
- Plan ahead: if a mortgage is two or three years away, the profit you declare now is what a lender will assess later.
- Claim accurately, not aggressively: claim every expense you are genuinely entitled to, but a clean, well-evidenced set of accounts is worth more than a rock-bottom profit.
- Keep your records and SA302s in order, because lenders cross-reference them against your bank statements.
- Choose the expense method deliberately: the mileage versus actual vehicle costs decision changes both your tax and your declared profit.
- Speak to a broker who understands self-employed lending, since some lenders and underwriters assess drivers more flexibly than others.
Tax and borrowing are one plan, not two
The mistake is treating your tax return and your mortgage plan as separate exercises. They are the same set of numbers viewed two ways. The right expense strategy is the one that is honest, claims what you are due, and is set with an eye on what you will need to evidence when you borrow. It is part of the wider financial planning for drivers that sits alongside pensions and protection.
If you are a driver planning to buy or remortgage in the next few years, it is worth lining up your accounts and your borrowing plan now. Tell us your situation through the form on this page and we will help you claim what you are entitled to while keeping your declared profit strong enough to support the mortgage you want.