Answers · UK 2025/26

What is a mortgage in principle and how long does it last?

A mortgage in principle (also called an agreement or decision in principle) is a lender's estimate of how much they might lend you, based on a quick assessment of your income and a soft credit check, before you have found a property. It typically remains valid for 60-90 days and helps demonstrate to estate agents and sellers that you are a serious, financeable buyer.

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A mortgage in principle is an early, indicative step in the home-buying process, useful for both budgeting and demonstrating credibility to sellers, though it is not a guarantee of final mortgage approval. **What it actually confirms** Based on information you provide about your income, outgoings, deposit, and a soft credit check (which does not affect your credit score), a lender gives an estimate of the maximum amount they would likely be willing to lend -- this is not a full, binding mortgage offer, since the lender has not yet verified your documents, assessed a specific property, or completed a full underwriting review. **Why it's useful before house-hunting** Having a mortgage in principle in hand before viewing properties helps you set a realistic budget, and estate agents often require one before booking viewings on properties (particularly in competitive markets), since it demonstrates you are a serious buyer who has at least begun the financing process. **How long it lasts** Most mortgage in principle certificates remain valid for 60-90 days, though this varies by lender -- if your house search takes longer than this, you may need to request a renewed or updated mortgage in principle, particularly if your financial circumstances have changed in the meantime. **Soft vs hard credit checks** A mortgage in principle typically uses a "soft" credit search, which is visible only to you (not other lenders) and does not affect your credit score -- this is different from the full mortgage application stage, which involves a "hard" credit search that is recorded and visible to other lenders, and multiple hard searches in a short period can slightly affect your credit score. **It's not a guarantee** A formal mortgage offer (the binding commitment) only comes after you have found a specific property, submitted a full application with supporting documents, and the lender has completed full underwriting including a valuation of that specific property -- your final borrowing amount or rate could differ from the mortgage in principle if your circumstances or the property itself raise concerns during full underwriting. **Worked example** Someone gets a mortgage in principle for £280,000 based on their £65,000 salary and £30,000 deposit. They then find a property for £300,000 and proceed to a full application -- if their financial situation is unchanged and the property passes valuation and survey checks, the final formal mortgage offer typically aligns closely with the original in-principle estimate, though it is not guaranteed to be identical. **Practical tip** Get a mortgage in principle from more than one lender if possible before committing to a full application, since different lenders can offer meaningfully different maximum borrowing amounts based on how they assess your specific income and outgoings.