What Is a Mortgage in Principle and How Long Does It Last

What it is

A Mortgage in Principle (MIP), also called a Decision in Principle (DIP) or an Agreement in Principle (AIP), is a written statement from a mortgage lender saying that, based on the information you have provided, they would in principle be willing to lend you a specified amount on a property purchase. It is not a formal mortgage offer and it is not legally binding on the lender, but it carries enough weight that estate agents and sellers treat it as credible evidence that you can afford to buy.

Why you need one

Most estate agents in 2026 will not show you properties unless you have a mortgage in principle ready. Sellers generally will not accept your offer without one. The agent uses it to filter serious buyers from window shoppers and to qualify offers. Without an MIP, you are at a significant disadvantage in any competitive market.

How to get one

You have three main routes:

1. Direct from a lender: most large UK lenders offer an online MIP application that takes 10 to 15 minutes. You provide income, expenses, address history, deposit amount, and consent to a credit check. The decision is usually instant.

2. Through a mortgage broker: a broker assesses your circumstances, recommends a lender, and submits the MIP application on your behalf. This is the right route if your situation is non-standard (self-employed, contract worker, recent credit issues, complex income).

3. Through a comparison site: some online comparison platforms can issue MIPs after a soft credit check. Useful for early-stage research but less robust than going direct or through a broker.

The application typically requires:

• Full name and date of birth
• Address history (3 years)
• Employment status and income
• Monthly outgoings
• Credit commitments
• Deposit amount
• Property price range
• Consent to a credit check

Hard credit check vs soft credit check

A "soft" credit check shows on your file but is not visible to other lenders and does not affect your credit score. A "hard" credit check is visible to other lenders and can have a small temporary effect on your score.

Most MIPs use a soft check. Some lenders use a hard check, especially if you are applying directly through a comparison site. If you are doing multiple MIPs to compare lenders, soft check is much better. Ask before you apply.

How long an MIP lasts

A standard MIP is typically valid for 30 to 90 days. Different lenders use different periods:

• Halifax, Nationwide, Santander: 90 days
• Barclays: 90 days
• HSBC: 60 days
• NatWest: 90 days
• Many building societies: 60 to 90 days

After the validity period, you can usually renew without a new credit check if your circumstances are unchanged. Estate agents will sometimes ask for a recent MIP (within the last 30 days) regardless of the lender's stated validity period.

Is an MIP a guarantee

No. The MIP is based on the information you provided plus a credit check. The lender has not verified your income, your employer, your address history, your bank statements, or the property itself. When you apply for the formal mortgage offer, the lender re-runs all these checks and can decline even if your MIP was approved.

The most common reasons MIPs are followed by declined formal applications:

1. Income verification: actual payslips or tax returns differ from what you stated

2. Bank statement issues: gambling, unexplained large deposits, frequent overdrafts

3. Property valuation comes in below offer: lender will not lend the full amount

4. Property is non-standard construction: lender refuses to lend on the property type

5. Buyer's circumstances changed: new job, new debt, missed payment

What to do with your MIP

1. Send a copy to your estate agent before viewing properties

2. Mention it in your offer so the seller knows you are credible

3. Use it to set your maximum budget when offering

4. Apply for the formal mortgage as soon as your offer is accepted

5. Tell your conveyancer so they can liaise with the lender

How to improve your chances

Before applying for an MIP:

1. Check your credit file at all three UK credit reference agencies (Experian, Equifax, TransUnion) and fix any errors

2. Pay down credit card balances to under 30% of the limit

3. Avoid new credit applications in the 3 months before

4. Make sure you are on the electoral roll at your current address

5. Have your last 3 months of bank statements ready

After you have an MIP

You can move quickly. The next steps are:

1. View properties

2. Make an offer

3. On acceptance, instruct a conveyancer

4. Apply for the formal mortgage

5. Book a building survey

6. Begin conveyancing

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• How long does conveyancing take
• What happens on completion day
• What is exchange of contracts