Mortgage in Principle (Agreement in Principle): How It Works, Credit Checks and How Long It Lasts

By Jake Stott, Knox Mortgages. Reviewed by an adviser authorised under Fort Advice Bureau, FCA FRN 972730. Published 27 September 2026. Last reviewed 27 September 2026.

A mortgage in principle is a written statement from a lender saying how much it would probably lend you, based on your income, outgoings and a credit check. It is also called an agreement in principle (AIP) or a decision in principle (DIP). All three names mean the same thing. It takes minutes, it is free, and it is not a mortgage offer.

This guide covers what a mortgage in principle actually tells you, whether it affects your credit score, which lenders use a soft search and how long each one lasts (checked on the lenders’ own websites in September 2026), how it differs from a full mortgage offer, when to get one, and exactly what to do if yours is declined.

What is a mortgage in principle?

A mortgage in principle is a lender’s early, conditional indication that it would lend you a stated amount, subject to a full application. You give the lender your income, regular outgoings, deposit, address history and the rough price you want to pay. The lender runs that through its affordability model and a credit search, then issues a certificate showing a maximum loan figure.

It answers one practical question: “roughly how much can I borrow, and will this lender entertain me?” It does not assess a specific property, it does not check your payslips or bank statements, and it does not fix an interest rate. The lender is relying on what you typed in. That is why an agreement in principle is quick and why it is only a starting point.

Estate agents ask for one because it shows you are a serious buyer who has spoken to a lender. Sellers in a competitive market will often favour an offer backed by an AIP over one that is not. For the full journey after this step, see our first-time buyer mortgage guide.

Agreement in principle, decision in principle, mortgage in principle: is there a difference?

No. They are three names for the same document. Lenders simply choose their own label. Barclays, Halifax and NatWest call it an Agreement in Principle. Nationwide, Santander, HSBC and Skipton call it a Decision in Principle. Brokers and buyers often say “mortgage in principle” or MIP. You may also see “approval in principle” or “offer in principle”, which again mean the same thing in a UK mortgage context.

The phrase “approved in principle” is used outside mortgages too, for personal loans and car finance. The meaning is identical: the lender is minded to lend based on the headline information, but has not yet verified anything and can still say no. If you have seen “loan approved in principle” on a personal loan application, treat it with the same caution. It is an intention to lend, not a guarantee of funds.

Term	Who tends to use it	What it means
Agreement in principle (AIP)	Barclays, Halifax, NatWest, Lloyds	Conditional indication of how much the lender would lend
Decision in principle (DIP)	Nationwide, Santander, HSBC, Skipton, most specialist lenders	Exactly the same thing
Mortgage in principle (MIP)	Buyers, estate agents, brokers	Exactly the same thing
Approved or offer in principle	Some lenders, loan providers	Exactly the same thing; not a formal offer

Does a mortgage in principle affect your credit score?

Usually no. Most mainstream lenders now run a soft credit search at agreement in principle stage. A soft search lets the lender read your credit file but is not visible to other lenders and has no effect on your credit score. The hard search, which does leave a footprint, normally happens later when you submit a full mortgage application.

There are two exceptions to know about. First, some lenders run a hard search at decision in principle stage, particularly certain specialist and adverse credit lenders, and historically some high street lenders did the same through the broker channel. Second, the search type on a lender’s consumer website is not always the same as on its broker platform. A broker should check before submitting, not after.

Why does it matter? One hard search is harmless. Several in a short window can look like credit hunger and can nudge a borderline case into a decline. The damage is usually small and fades within 12 months, but it is avoidable. If your credit history is not perfect, read what credit score you need for a mortgage before you apply anywhere.

Which lenders use a soft search for an agreement in principle?

We checked each lender’s own public mortgage in principle page in September 2026. The table below uses their wording. Lenders change their process without notice, so treat this as a snapshot, not a guarantee.

Lender	What they call it	Credit search at AIP stage	How long it lasts	Time to complete
Barclays	Agreement in Principle	Soft. “It doesn’t involve a hard credit check”	Usually 90 days	About 10 minutes
Nationwide	Decision in Principle	Soft. Does not affect your credit rating	90 days, renewable in the Mortgage Hub	Around 20 minutes
NatWest	Mortgage Agreement in Principle	No “full” credit check; no impact on your score	30 days	Under 10 minutes
Santander	Decision in principle	Soft for the online DIP; hard search at full application	60 days	Instant decision
HSBC	Decision in Principle	“May involve a soft credit search”, no effect on your rating	HSBC says typically 60 to 90 days	Usually same day
Halifax	Agreement in Principle	Soft, per Halifax’s own guidance	Usually 30 to 90 days	Minutes online
Skipton Building Society	Decision in Principle	Soft; hard search only at full application	30 days	About 5 minutes
Kensington (specialist, broker only)	Decision in principle	Soft; hard search at full application	Usually 60 days	Submitted by your broker

Sources: each lender’s public decision or agreement in principle page, checked September 2026. The Halifax figure comes from Halifax’s published guidance; its page was unavailable when we rechecked, so confirm before relying on it. Search type through a broker can differ from the lender’s direct website.

How long does an agreement in principle last?

An agreement in principle usually lasts between 30 and 90 days, depending on the lender. From the table above, NatWest and Skipton give 30 days, Santander and Kensington give 60 days, and Barclays and Nationwide give 90 days. HSBC describes a typical range of 60 to 90 days.

If yours expires before you find a property, you simply get a new one. Nationwide lets you renew through its Mortgage Hub if nothing significant has changed. With most lenders a fresh AIP is another soft search, so renewing costs you nothing on your credit file. The one thing to watch is whether your circumstances have changed since the first one: a new job, a new car finance agreement or a pay rise can all move the figure up or down.

Practical rule: do not get an AIP months before you are ready to view. Get it when you are about to start booking viewings, so it is still live when you make an offer. Agents often want to see a certificate dated within the last few weeks.

How long does it take to get a mortgage in principle?

Minutes, in most cases. Barclays quotes about 10 minutes, NatWest under 10 minutes, Nationwide around 20 minutes and Skipton about 5 minutes. Santander and HSBC say you get an instant or same day decision. Where a broker submits to a specialist lender, the automated decision usually still comes back within the hour, and a manual referral normally takes one to two working days.

What slows it down is missing information, not the lender. Have these ready before you start:

• Gross annual income for each applicant, plus any bonus, overtime or commission
• Monthly credit commitments: loans, car finance, credit card balances, student loan
• Regular costs such as childcare and dependants
• Three years of address history
• Deposit amount and where it comes from (savings, gift, equity)
• Rough purchase price and the property type if you know it

If you are self-employed, lenders will ask for your latest year’s figures or a two year average at this stage. See our self-employed mortgage guide for which figure each lender uses.

What an agreement in principle is not

This is where most buyers get caught out. An agreement in principle is not any of the following:

• Not a mortgage offer. The lender has verified nothing. It can still decline you at full application.
• Not a rate lock. An AIP does not reserve an interest rate or product. Rates are secured only when the full application is submitted, and even then only for the lender’s own reservation period.
• Not an assessment of the property. The valuation comes later. A property the lender will not lend on (non-standard construction, short lease, flat above a takeaway) is not picked up at AIP stage.
• Not a promise of the full amount. The figure is a maximum. Once payslips and bank statements are checked, the final loan can be lower.
• Not binding on you. You are free to apply with a different lender later. An AIP with one bank does not commit you to that bank.
• Not a guide to the best deal. One lender’s AIP tells you what that lender would do, not what the market would do.

Does an agreement in principle lock in a rate?

No. An agreement in principle does not lock in an interest rate or reserve a product. It only records how much the lender is prepared to consider lending. Rates can be withdrawn or repriced at any time, sometimes with less than 24 hours’ notice, and holding an AIP gives you no protection against that.

A product is secured when the full mortgage application is submitted with the product selected. Most lenders then hold that rate through to offer, and the offer itself usually stays valid for around six months (Virgin Money and Kensington both quote 180 days for a standard purchase; Virgin Money gives 210 days on new builds). Some lenders will also let you “reserve” a product early by paying a booking fee, but that is a product reservation, not an AIP.

If rates are moving and you have a property lined up, the fastest way to protect yourself is to move from AIP to full application quickly with all your documents ready. A broker can often submit within a day of your offer being accepted.

What is the difference between an AIP and a full mortgage offer?

An agreement in principle is based on what you declare. A full mortgage offer is based on what the lender has verified: your documents, your full credit file, the property valuation and an underwriter’s review. The offer is the only document that commits the lender to lend, subject to its conditions.

	Agreement in principle	Full mortgage offer
When you get it	Before or while house hunting	After your offer on a property is accepted and you apply
Time to get it	Minutes to 2 working days	Typically 2 to 4 weeks from full application
Credit search	Usually soft	Hard, leaves a footprint
Documents checked	None	Payslips, bank statements, ID, deposit proof, tax returns if self-employed
Property valued	No	Yes
Rate secured	No	Yes, the product on the application
How long it lasts	30 to 90 days	Usually around 6 months
Can the lender say no afterwards?	Yes, easily	Only if something material changes or proves untrue

For how long each stage after this takes, see how long a mortgage application takes, and for what the valuer is actually checking, see our mortgage valuation guide.

Worked example: why the AIP figure can drop at full application

Take a couple buying their first home. One earns £34,000 and the other £28,000, so combined gross income is £62,000. They type that in and receive an AIP for £279,000, which is 4.5 times income (£62,000 x 4.5 = £279,000).

At full application the underwriter finds three things the AIP did not capture properly:

• A £310 a month car finance agreement with 30 months left. Over a year that is £3,720 of committed spending.
• £4,000 of the second applicant’s income is overtime. This lender only counts 50% of overtime, so £2,000 is removed.
• Nursery fees of £650 a month, declared at AIP as £400.

Assessed income falls to £60,000 and the lender’s affordability model now shows higher monthly commitments. Its maximum drops to around £252,000. On a £280,000 purchase with a £28,000 deposit, they needed £252,000 exactly, so the case still works, but only just. Had they offered £290,000 based on the AIP, they would have been £10,000 short.

The lesson: an AIP is only as accurate as the information going in. Declare everything, use real figures, and do not bid right up to the AIP ceiling. Our guide to how lenders calculate affordability shows the full method, and the how much can I borrow guide covers income multiples lender by lender.

When should you get a mortgage in principle?

Get your mortgage in principle just before you start booking viewings. That way the certificate is still in date when you make an offer, and the agent can see you have a lender behind you. Getting one six months early is pointless because it will expire (NatWest and Skipton give only 30 days) and your circumstances may change.

There are three other good moments to get one:

• Before you set your budget. Knowing your realistic ceiling stops you falling for a property you cannot finance.
• Before you sell, if you are moving home. It confirms your onward purchase is fundable before you commit to a sale.
• Before changing jobs. Some lenders need you past probation or three months into a new role. An AIP tells you whether to wait.

If you already know your deposit is partly gifted, flag it at AIP stage. Some lenders cap gifted deposits or restrict who can give them. Our gifted deposit guide explains the rules.

Can you be declined after an agreement in principle?

Yes. An agreement in principle is conditional, and lenders decline at full application more often than most buyers expect. These are the common reasons and the fix for each.

Why it fails after the AIP	What the lender found	The fix
Income mismatch	Payslips or tax returns show less than declared, or variable pay is only partly counted	Declare basic pay and variable pay separately; use the lender’s own treatment of bonus and overtime
Bank statement conduct	Gambling, regular overdraft use, payday loans, undeclared debts	Clean up three months of statements before applying; declare every commitment
Hard search detail	A recent missed payment or default the soft search did not weigh heavily	Check all three credit files first; choose a lender whose policy accepts the issue
Property	Down-valuation, non-standard construction, short lease	Check property criteria before offering; keep a buffer in your deposit
Changed circumstances	New job, new car finance, smaller deposit since the AIP	Take no new credit and avoid job moves until the offer is issued
Deposit source	Funds cannot be traced to anti money laundering standards	Keep a clear paper trail; get a gifted deposit letter signed early

Most of these are avoidable with preparation. A broker reads your bank statements and credit file before the application goes in, which is where most declines are caught early.

What should you do if your agreement in principle is declined?

Stop and diagnose before you try anywhere else. A declined AIP on a soft search has not damaged your credit score, but spraying applications across several lenders could, if any of them use a hard search. Work through these steps in order:

1. Check all three credit reports. Experian, Equifax and TransUnion. Lenders use different agencies, and errors on one are common. Correct wrong addresses, old accounts and missing electoral roll entries.
2. Register on the electoral roll at your current address if you are not already. It is one of the most common and easiest fixes.
3. Look at the numbers honestly. Was the loan amount too high for the income? Were debts pushing affordability over the edge? Clearing a small balance or a car finance agreement can change the answer.
4. Ask why. Lenders rarely give detail, but a broker can often find out whether the issue was credit scoring, affordability or policy.
5. Match the lender to the problem. High street lenders credit score tightly. Specialist lenders accept defaults, CCJs, recent self-employment or low credit scores that a bank will not. Our bad credit mortgage guide shows which issues specialists accept.

If you want to fix the file yourself first, our guide to improving your credit score for a mortgage sets out a 90 day plan.

Is it better to get an AIP from a bank or through a broker?

A bank’s AIP tells you what that one bank will do. A broker’s AIP is placed with the lender most likely to approve your full case, which is a different thing. If you are a straightforward employed buyer with a clean credit file, going direct is quick and perfectly reasonable. If anything about your case is unusual, a direct AIP can pass and then fail at full application because the bank’s criteria never suited you.

Examples where lender choice matters from day one: self-employed for under two years, contractors on day rates, bonus or commission heavy income, a gifted deposit, any missed payments in the last three years, a non-standard property, or buying with someone who is not on the mortgage. A whole-of-market broker checks criteria before the AIP, not after the decline. See our comparison of using a mortgage broker versus going to your bank.

At Knox, we run the AIP with the lender we would actually submit the full application to, so the certificate you show the estate agent is one that should stand up at underwriting.

An illustrative Knox case: the AIP that would have failed

This is an anonymised, illustrative case based on the type of situation we see regularly. Details have been changed.

A first-time buyer in Stockport, employed for eleven months after two years as a sole trader, got an online AIP from her own bank for £210,000. She found a flat, had an offer accepted and was about to apply. On our discovery call we noticed two things. Her bank requires two years of continuous employment or two years of self-employed accounts, and she had neither in one continuous form. And a £900 credit card balance was reported as late once, eight months earlier, which her bank’s scorecard penalises.

The AIP had passed because it did not test either point. A full application with her bank would very likely have been declined, leaving a hard search and a nervous seller. Instead we placed a fresh AIP with a lender that counts combined employed and self-employed history and accepts a single late payment over six months old. The full application went in within two days of her documents arriving and the offer came back in 16 working days, for the same loan amount.

Do you need an AIP for a remortgage, buy-to-let or bridging loan?

For a remortgage, you do not need an AIP to show anyone, but lenders still run a decision in principle as the first step of the application. It is often completed on the same day as the full application. See our remortgage guide for the process.

For buy-to-let, a decision in principle works the same way, but the lender is mainly testing the rental figure against its interest cover ratio rather than your salary. Limited company purchases also need the company details at DIP stage. Our buy-to-let mortgage guide explains the rent tests.

Bridging lenders issue their own “terms” or “indicative terms” rather than an AIP. They are driven by the property and the exit plan more than by income, and they are normally issued within 24 to 48 hours.

Frequently asked questions

Does a mortgage in principle affect your credit score?

Usually not. Barclays, Nationwide, Santander, HSBC, Skipton and Kensington all describe a soft search at agreement in principle stage, and NatWest says it does not run a full credit check. A soft search is invisible to other lenders. Some specialist lenders still use a hard search at DIP stage, so ask before applying.

How long does an agreement in principle last?

Between 30 and 90 days, depending on the lender. NatWest and Skipton give 30 days, Santander and Kensington 60 days, and Barclays and Nationwide 90 days (September 2026). If it expires, you can usually get a new one on another soft search with no impact on your credit file.

Is a decision in principle the same as an agreement in principle?

Yes. Decision in principle, agreement in principle and mortgage in principle are three names for the same document. Each lender picks its own label. None of them is a mortgage offer, and none of them commits you to that lender.

Does an agreement in principle lock in a rate?

No. An AIP does not reserve a rate or product. The rate is secured when the full application is submitted with that product selected. If rates are rising, moving quickly from AIP to full application is the only reliable way to protect a deal.

Can I get an agreement in principle with no credit check?

Not a genuine one. Every lender checks your credit file before issuing an AIP. The good news is that most use a soft search, which does not affect your score. Online calculators that ask for no personal details are estimates, not agreements in principle.

Can a mortgage be declined after a decision in principle?

Yes. The AIP is based on what you declared. At full application the lender checks your documents, runs a hard credit search and values the property. Income that does not match, undeclared debts, a poor valuation or a change of job can all lead to a decline.

How many agreements in principle can I get?

There is no limit, and soft-search AIPs do not harm your score. The risk is hard-search DIPs: several in a few weeks can look like credit hunger. Get one or two targeted AIPs rather than trying every bank, and ask which search type each lender uses.

Is there a downside to getting a mortgage in principle?

Very little, provided it is a soft search. The main risks are relying on it as a guarantee, bidding right up to the AIP ceiling, or letting it expire. An AIP from a lender whose criteria do not suit you can also give false confidence.

Want an AIP that will stand up at full application? Book a free, no-obligation discovery call and we will match you to the right lender before anything is submitted.

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Knox Mortgages is a trading style of Fort Advice Bureau which is regulated and authorised by the FCA to conduct Mortgage and Protection business, FRN: 972730