| Also called | Agreement in principle (AIP) or decision in principle (DIP) |
|---|---|
| Typical validity | 30 to 90 days |
| Credit check | Soft or hard, depending on the lender |
| Binding? | No; the full application and valuation still apply |
| Cost | Usually free |
What is a mortgage in principle?
A mortgage in principle (MIP) is an early indication from a lender of how much it may lend. The lender runs your details through its affordability model and checks your credit file. If you pass, it issues a certificate with a figure.
It is not a full application. The lender has not yet checked your documents, valued the property or underwritten the case.
Mortgage in principle, agreement in principle (AIP) and decision in principle (DIP) all mean the same thing. Different lenders use different names. Some call it a mortgage promise. Whatever the name, the figure is only as reliable as the information you give.
Does a mortgage in principle affect your credit score?
It depends on the lender. Some use a soft search that other lenders cannot see and that does not affect your score. Others use a hard search, which is visible on your file.
One hard search is unlikely to matter much. Several in a short period can make lenders cautious. A broker can choose a lender likely to accept your case first time, which reduces unnecessary searches.
How long does a mortgage in principle last?
Most last between 30 and 90 days. If it expires before you find a property, you can usually renew it. The lender may run a fresh credit check.
If your income, debts or deposit change, get a new one. An out-of-date figure can mislead you and the seller.
Timing matters in a busy market. Getting an MIP a few weeks before you start viewing gives you a clear budget without it lapsing too soon. If you are buying and selling at the same time, base the figure on the deposit you expect after your sale.
What information do you need for a mortgage in principle?
- Name, date of birth and three years' address history
- Employment type and income, including bonuses
- Monthly commitments such as loans, credit cards and childcare
- Deposit amount and expected purchase price
- Details of any adverse credit
Accuracy matters. If the figures on your later application differ, the lender may lend less or decline.
How is a mortgage in principle different from a mortgage offer?
A mortgage in principle is an early indication. A mortgage offer is the lender's formal, written agreement to lend on a specific property, issued after full checks.
| Mortgage in principle | Mortgage offer | |
|---|---|---|
| When | Before you find a property | After your offer is accepted and you apply |
| Documents checked | Usually none | Income, ID, bank statements, deposit |
| Property valued | No | Yes |
| Typical validity | 30 to 90 days | Often around six months |
| Binding on the lender | No | Yes, subject to its conditions |
Should complex cases get a manual mortgage in principle?
Often, yes. Automated systems work best for straightforward salaried income. If you are self-employed, a company director, paid in a foreign currency, or have bonus-heavy pay, an automated MIP may understate or overstate what the lender will finally offer.
Some lenders, including private banks, will review a case manually before issuing an MIP. This takes longer but gives a more reliable figure. A broker can also check the lender's income policy before applying, so the figure you show the agent is one the lender is likely to stand behind.
This matters most at higher loan sizes, where a gap between the MIP and the final offer can put a purchase at risk.
Why do estate agents ask for a mortgage in principle?
Sellers want to know your offer is realistic. Many agents ask for an MIP before taking an offer seriously, especially in competitive markets such as prime central London.
It also helps you. You know your budget before viewing, and you can move quickly when you find the right home. Our how much can I borrow guide explains the affordability side.
Can a mortgage be declined after a mortgage in principle?
Yes. An MIP is not a guarantee. Common reasons for a later decline include:
- Income that cannot be evidenced as stated
- A lower valuation than the purchase price
- A property the lender will not accept, such as some high-rise flats or non-standard construction
- Changes to your credit file or circumstances
- Lender criteria changing before you apply
OMB checks your documents and the property type against lender criteria early, which reduces surprises later.
Sources
Checked October 2026. Rules and tax treatment can change, so confirm the current position before acting.
- MoneyHelper: What happens when I get a mortgage in principle?
- MoneyHelper: Should you use a mortgage adviser?
Frequently asked questions
Is a mortgage in principle a guarantee?
No. It shows what a lender may lend based on the information given and a credit check. The lender still needs to verify your documents, value the property and underwrite the application before making a formal mortgage offer. Treat it as a guide, not a promise.
Does a mortgage in principle do a hard credit check?
Some lenders use a soft search that does not affect your score. Others use a hard search that is visible to other lenders. Ask before you apply, or use a broker who knows which lenders use which method. Either way, check your credit report first.
How long does it take to get a mortgage in principle?
Often minutes online, once your details are entered. Complex cases, such as self-employed income or foreign nationals, may need a manual review by the lender, which can take longer. Having your income figures, commitments and address history to hand makes it quicker.
Can I get more than one mortgage in principle?
Yes, there is no limit. But several hard searches close together can make lenders cautious. It is better to get one from a lender that suits your situation than to apply widely. If you do apply to several, choose lenders that use a soft search where possible.
Do I need a mortgage in principle before viewing houses?
It is not a legal requirement. Many estate agents ask for one before accepting an offer, and it helps you set a realistic budget. Getting one early is sensible. In competitive parts of London, some agents will not book second viewings without one.
Can I use a mortgage in principle from one lender and apply with another?
Yes. An MIP does not commit you to that lender. You can apply with any lender when you find a property. Estate agents simply want evidence that borrowing is realistic, though a new lender will run its own checks. Your final loan may differ.
Does a mortgage in principle cost anything?
Lenders do not usually charge for one. Some brokers include it in their overall service. Any broker fee should be explained in writing before you proceed, along with when it is payable. Be cautious of anyone charging a fee simply to issue an MIP.
What happens after a mortgage in principle?
Once your offer on a property is accepted, you submit a full application with documents. The lender values the property and underwrites the case. If everything checks out, it issues a formal mortgage offer. Your solicitor then carries out searches and legal work before exchange and completion.
Important: This guide is general information, not personal advice. Rules, rates and lender criteria change; speak to an adviser about your circumstances. Your home may be repossessed if you do not keep up repayments on your mortgage.