A mortgage agreement in principle (AIP) is an early indication from a lender of how much it may be willing to lend you, based on the information you give and some initial checks. You might also see it called a mortgage in principle or a decision in principle. It helps you set a realistic budget and shows sellers and estate agents that you’re a serious buyer, but it isn’t a guaranteed mortgage and it doesn’t mean your application has been approved.
You don’t legally need an AIP to buy a home, but having one before you start viewing makes your search more focused and your offers more credible. In this guide, we explain what an AIP does and doesn’t do, when to get one, how credit checks work, how long it lasts and what happens when you move on to a full mortgage application.
What Is a Mortgage Agreement in Principle?
An AIP is a written or digital statement showing that a lender has reviewed enough initial information to estimate what it might lend you. The lender usually looks at your income, regular outgoings, deposit and credit history. The result typically shows a maximum borrowing figure or an approximate mortgage budget.
That figure is a ceiling, not a target. Your budget also needs to cover council tax, energy, insurance, food, transport, maintenance, childcare and the possibility of interest rate changes. MoneyHelper’s mortgage affordability calculator is a useful sense-check, though any calculator result is an estimate and every lender applies its own criteria.
AIP, MIP and DIP: Are They Different?
In everyday UK property conversations, agreement in principle (AIP), mortgage in principle (MIP) and decision in principle (DIP) all describe the same early-stage assessment. The label matters less than the details: check whether the lender used a soft or hard credit search, how long the result is valid for and what still needs to be verified.
What Does an AIP Actually Tell You?
An AIP mainly gives you an indicative borrowing limit and a clearer idea of the price range to search in. It helps you avoid viewing homes outside your budget and gives the agent useful information when comparing your offer with others. Getting an AIP from one lender doesn’t commit you to taking a mortgage with that lender.
- An estimated maximum loan, subject to full underwriting and the property being acceptable to the lender.
- An early view of whether your income, outgoings and credit history fit the lender’s criteria.
- A useful document to share with the estate agent when you make an offer.
- A reference point for comparing the loan amount with your deposit and total buying costs.
It doesn’t confirm the property’s value, guarantee the lender will accept the home, fix your final interest rate or replace a formal mortgage offer. You’ll still need money for legal fees, surveys, searches, moving costs, Stamp Duty where it applies and other buying expenses. Our guide to the hidden costs of buying a house covers these in detail.
When Should You Get a Mortgage in Principle?
For most buyers, the right time is before serious viewings and before making offers. Get one too early and your income, debts, deposit or the lender’s criteria may change before you’re ready. Leave it too late and it’s harder to show an agent you’re ready to proceed. A sensible approach is to work out your budget first, gather your documents, then get an AIP when you’re ready to search actively.
Before You Start Viewing
An AIP gives your search a financial boundary. For example, with a £50,000 deposit and an AIP showing you could borrow £250,000, your headline budget might be £300,000 before buying costs. That doesn’t mean every £300,000 home is affordable for you: keep money aside for fees, and don’t borrow the maximum just because a lender may offer it.
Before You Make an Offer
When you make an offer, an AIP strengthens the picture you give the agent, alongside your deposit, chain position and solicitor details. It helps the conversation, but it doesn’t guarantee the seller will accept your offer.
How to Get a Mortgage in Principle
You can usually get an AIP directly from a lender or through a mortgage adviser, online, by phone or at an appointment. An adviser can explain which products and criteria may suit you and can be especially helpful if your circumstances are less straightforward, such as self-employment, variable income or past credit problems. Our mortgage services team offers a free, no-obligation consultation to talk through your options.
Give accurate figures rather than rounding up. You may be asked for:
- Your income, employment status and how long you’ve been in your job.
- Regular outgoings, credit commitments, childcare and other significant costs.
- The size and source of your deposit.
- Your address history and personal identification details.
- Details of any existing mortgage or a home you need to sell.
An online result can be quick, but accuracy matters more than speed. If your circumstances change, or the price or deposit changes significantly, ask whether your AIP should be updated.
Does an AIP Affect Your Credit Score?
It depends on the lender and the type of credit search it uses. Some lenders carry out a soft search, which doesn’t affect your credit score, while others carry out a hard search that’s recorded on your credit file and visible to other lenders.
Don’t assume every lender works the same way. Before applying, ask whether the check is soft or hard and whether it will be recorded. Avoid making lots of applications in a short space of time without knowing the search type, especially if you’re comparing several lenders. This is one area where speaking to an adviser first can save you trouble.
What If Your AIP Is Declined?
A declined AIP doesn’t mean you can’t buy a home. It means that lender’s initial criteria weren’t met based on the information it had. Common factors include affordability, credit history, deposit size, employment pattern, existing commitments or a mistake in the information provided. Pause before applying again, check your credit files for errors and consider personalised advice if your situation is complex.
AIP vs Formal Mortgage Offer
| Feature | Agreement in principle | Formal mortgage offer |
|---|---|---|
| Purpose | An indicative borrowing estimate, usually before you’ve chosen a property. | The lender’s formal offer for a specific property and application. |
| Checks | Initial information and credit check; scope varies by lender. | Detailed income, affordability, credit, identity and property checks. |
| Property | The specific property usually hasn’t been assessed. | A valuation and property suitability are considered. |
| Certainty | Not guaranteed and can be revised or withdrawn. | A formal offer, subject to its conditions and expiry date. |
The formal mortgage offer normally follows a full application once your offer on a home has been accepted. The lender may ask for payslips, bank statements, proof of deposit, tax documents, ID and property details, and will usually arrange a valuation. Don’t treat an AIP as a green light to exchange contracts or pay non-refundable costs.
What Happens After an AIP?
Once your offer is accepted, tell your lender or adviser you want to proceed. The next steps usually include a full application, document checks, an affordability assessment, a property valuation and underwriting. The lender then decides whether to issue a formal mortgage offer and on what terms.
- Confirm the purchase price, deposit and mortgage amount.
- Submit your full application and supporting documents promptly.
- Answer questions clearly about income, debts, gifted deposits or unusual transactions.
- Arrange your own survey separately from the lender’s valuation if appropriate.
- Wait for the formal offer before treating your mortgage as approved.
Your mortgage is only one part of the purchase. Your conveyancer still needs to handle searches, enquiries and exchange of contracts, and if you’re buying in a chain, keep the estate agent updated on your finance and legal progress. Some of the sellers we work with use reservation agreements, a legally binding agreement entered into once a sale is agreed, to create a more committed transaction. If you’re asked to sign one, ask your solicitor to explain it first.
Common Reasons an AIP Is Declined
Lenders use different affordability models and risk criteria, so one lender may decline an AIP that another would accept. Common reasons include:
- Income that’s too low, irregular or can’t be evidenced in the way the lender needs.
- High monthly commitments, unsecured borrowing or recent missed payments.
- A deposit or source of funds that can’t yet be verified.
- Credit file information that doesn’t match the application.
- A loan request that’s high compared with income or the lender’s policy.
- Employment, residency, self-employment or property circumstances that need specialist assessment.
The best response is to understand the reason, not to guess. Never adjust figures to make an application look stronger. Ask what evidence is needed and take advice before submitting another application.
Practical Advice for First-Time Buyers and Home Movers
First-Time Buyers
A mortgage in principle can make an unfamiliar process feel much more manageable. Start with the total cash you’ll need, not just the deposit: budget for conveyancing, a survey, mortgage fees, moving costs, insurance and any Stamp Duty. Keep a contingency too. When viewing, ask about lease length, service charges, council tax and likely maintenance, not just the monthly mortgage payment.
Home Movers
If you already own a home, what you can borrow may depend on your sale price, outstanding mortgage, equity, any early repayment charges and whether you’ll port your current mortgage or take out a new one. Tell your lender and the selling agent if your purchase depends on your sale. Your AIP may need updating once your home has been valued or your mortgage balance is confirmed. If you haven’t had a valuation yet, we’re happy to provide a free, no-obligation valuation.
Making an Offer With Confidence
When you offer on one of our listings, be ready to tell us about your deposit, AIP, chain position and solicitor. While you compare homes, keep your real budget in view as you browse our properties for sale. An AIP should support a clear conversation; it should never push you into offering more than you can comfortably afford.
Frequently Asked Questions
Do you need a mortgage in principle to make an offer?
No, it isn’t a legal requirement, but agents and sellers often see it as useful evidence that you’ve checked what you can afford. Cash buyers would normally provide proof of funds instead.
How long does a mortgage in principle last?
There’s no standard expiry. Many AIPs are valid for somewhere between 30 and 90 days, depending on the lender. Check the date and conditions on your own AIP and ask for an update if it expires or your circumstances change.
Is an AIP the same as a mortgage offer?
No. An AIP is an early estimate. A formal mortgage offer follows a full application and further checks on your finances and the specific property.
Can a mortgage in principle be withdrawn?
Yes. A lender can revise or withdraw an AIP if your information changes, its criteria change, the full checks produce a different result or the property isn’t suitable security.
How Carter Remy Estates Can Help
An AIP is most useful as part of a wider buying plan. Our team can provide free independent mortgage advice and offers a free, no-obligation consultation through our mortgage services page, so you can understand your options before you start viewing. Any mortgage decision should be based on your own circumstances and the terms offered by your lender. Your home may be repossessed if you do not keep up repayments on your mortgage.
If you’re ready to search in South Essex, Thurrock or East London, browse our latest homes for sale and book viewings with our team. Selling as well? Our guide on how to prepare your house for sale is a good place to start. For a tailored conversation, contact our team or call 01268 727757 (Basildon) or 01375 511411 (Grays).
