Mortgage in Principle Guide
Everything you need to know before you start house-hunting: what a Mortgage in Principle is, how to get one, what documents you’ll need, and how it fits into your wider mortgage journey.
What Is a Mortgage in Principle?
A quick explainer before you dive into the application process.
Definition & Purpose
Why lenders and estate agents both ask for this document
A Mortgage in Principle (MIP) — also known as an Agreement in Principle (AIP) or Decision in Principle (DIP) — is a document from a lender stating how much they would be willing to lend you, based on a brief review of your income, outgoings, and credit history.
It is not a formal mortgage offer and is not legally binding on either side. Instead, it acts as an early indicator of your borrowing power, giving you a realistic budget before you start viewing properties.
Estate agents will often ask to see a Mortgage in Principle before they submit an offer to a seller on your behalf, since it shows you have already taken a first, verified step towards financing the purchase.
Quick Facts
Key things to know before you apply
How to Get a Mortgage in Principle
The process is usually quick and can often be completed online in under 15 minutes.
Gather Your Basic Details
You’ll need your income, employment status, monthly outgoings, existing debts, and the size of deposit you’re planning to put down.
Choose a Lender or Broker
Apply directly through a bank or building society, or use a mortgage broker to compare Mortgage in Principle offers across multiple lenders at once.
Complete a Soft Credit Check
Most lenders run a soft search that does not affect your credit score and is invisible to other lenders, letting you shop around freely.
Receive Your Estimate
The lender confirms an indicative amount they may lend you. You can then use this figure, together with your deposit, to set a realistic property budget.
Documents You’ll Typically Need
Having these ready in advance will speed up your application, whether you apply online, by phone, or through a broker.
| Document | Why It’s Needed | Required For |
|---|---|---|
| Proof of ID | Confirms your identity (passport or driving licence) | All applicants |
| Proof of address | Recent utility bill or bank statement | All applicants |
| Payslips (last 3 months) | Verifies employed income | Employed applicants |
| Tax returns / SA302s | Verifies self-employed income | Self-employed applicants |
| Bank statements | Shows spending patterns and outgoings | All applicants |
| Deposit evidence | Confirms available savings or gifted deposit | All applicants |
Mortgage in Principle vs. Full Mortgage Offer
These terms are often used interchangeably, but they represent very different stages of the buying process.
| Stage | When It Happens | Credit Check | Legally Binding? |
|---|---|---|---|
| Mortgage in Principle | Before you start house-hunting | Usually soft | No |
| Full Mortgage Application | After your offer is accepted | Hard search | No, until offer issued |
| Formal Mortgage Offer | After underwriting & valuation | Already completed | Yes, on both sides |
Mortgage in Principle FAQ
Answers to the questions first-time buyers and movers ask most often about getting a Mortgage in Principle.
A Mortgage in Principle (also called an Agreement in Principle or Decision in Principle) is a statement from a lender confirming, in principle, how much they might be willing to lend you based on a quick review of your income and outgoings. It is not a formal mortgage offer.
Most lenders use a soft credit check to produce a Mortgage in Principle, which does not affect your credit score and is invisible to other lenders. A small number of lenders use a hard check, which does leave a visible mark, so it is worth asking before you apply.
A Mortgage in Principle is typically valid for 60 to 90 days, depending on the lender. If your house search takes longer than this, you can usually ask the lender to renew or reissue it.
It is not a legal requirement, but most UK estate agents will ask for a Mortgage in Principle before they pass your offer to the seller, as it demonstrates you are a serious and financially credible buyer.
No. A Mortgage in Principle is an indicative estimate based on limited information. The lender will still carry out a full affordability assessment, credit check, and property valuation before issuing a formal mortgage offer.