Written by Count Ready · Updated 7 September 2026 · Guidance for UK first-time buyers and other homebuyers.
What does a mortgage in principle actually tell you?
It gives a starting indication of borrowing based on details such as your income, commitments and deposit. Read the document carefully: it should make clear who issued it, what it says and any conditions or expiry date.
| Stage | What it means |
|---|---|
| Calculator or initial estimate | A planning figure based on the information entered. It is not a lender’s decision. |
| Lender AIP or DIP | A provisional assessment. Further evidence, property checks and the full application remain. |
| Formal mortgage offer | An offer for the application and property after the lender’s required assessment. Read its conditions and expiry date with your adviser and conveyancer. |
Some brokers also provide their own borrowing or affordability certificates. Ask whether a document records an actual lender decision or the broker’s estimate; similar labels do not necessarily mean the same checks have taken place.
An AIP is not a reason to spend up to the maximum shown. Work out the monthly payment you can manage and keep money for buying costs and unexpected expenses. Our affordability calculator offers a rough starting estimate, while the repayment calculator lets you explore payments using a rate and term you enter. Neither provides a lending decision.
When should you get an agreement in principle?
It can be useful when you are moving from general research to actively viewing homes or preparing to make an offer. You can usually discuss an AIP before choosing a property.
There is no general legal requirement to have one before viewing or making an offer. An estate agent may ask for evidence that you can fund the purchase, and an AIP can help with that discussion. It does not guarantee that the seller will accept your offer.
If you are still saving or expect your income, job or buying arrangements to change, start with a budget discussion. An AIP obtained too early may need updating before it is useful.
When sharing evidence with an agent, ask what they need. A certificate is different from a full credit report or a collection of bank statements; share personal information only through an appropriate route.
What information do you need?
Prepare accurate details for everyone applying. The lender’s questions and evidence requirements vary, but the discussion commonly covers:
- Personal details: names, dates of birth, address history and residency information where relevant.
- Income: employment, pay and other income you want considered. Explain variable earnings or self-employment rather than treating every income type as automatically acceptable.
- Spending and debts: credit commitments, childcare, maintenance and other regular outgoings.
- Deposit: the amount available, its source and any money you need to keep for purchase costs.
- Plans: approximate property budget, intended mortgage term and whether you are applying alone or jointly.
Some initial processes use the figures you provide without reviewing every document immediately. That does not remove the later evidence requirements. Use payslips, statements or relevant business records to check your answers instead of estimating carelessly.
If part of the deposit is a gift, explain the donor and arrangement. Our gifted-deposit guide covers the evidence to prepare. For a joint application, both applicants’ finances matter.
Does an AIP affect your credit score?
Ask which type of search will be used before proceeding. A soft search does not affect your credit score and is not shown to other lenders as a credit application, although you may see it on your own report. A hard search leaves a record that other lenders can see and may affect your score.
The process varies by lender and stage. For example, Nationwide currently states that its DIP uses a soft credit check; that is its policy, not a promise about every provider. The full mortgage application can involve further credit checks.
Check your credit reports for errors and explain any known issues before applying. Avoid making repeated applications simply to chase the largest figure, particularly without knowing which searches are involved. A credit-reference agency’s score is not a mortgage approval threshold. Read more about how AIP credit checks work, including repeat requests and declines.
How long is it valid, and does it reserve a rate?
Check the expiry date and conditions on the document. Validity differs between lenders; it should not be assumed from a general guide. Nationwide’s published DIP period is currently 90 days, but this does not set the period for other lenders.
An AIP does not normally reserve a particular mortgage rate or product. Ask separately what is needed to secure a chosen deal and what happens if products change before the application.
Tell your adviser if your income, job, debts, deposit or applicants change, even before the expiry date. If the AIP expires, ask whether an update or a new assessment is needed and what credit check that involves. Our existing AIP duration guide covers expiry and renewal; the issuing lender’s current terms take priority.
What happens after you get an AIP?
- Review the result. Check the amount, assumptions and conditions against your real buying budget. Ask about anything unclear.
- Check the property. Before relying on the AIP for an offer, discuss the intended property type, deposit and any unusual features with your adviser.
- Choose a suitable mortgage. Compare the available rate, fees, term and flexibility. The lender used for an initial AIP may not remain the most suitable choice.
- Prepare the full application. Supply the requested income, identity, deposit and other evidence. The lender assesses the application and arranges its property checks.
- Review any formal offer. If an offer is issued, understand its conditions and expiry. Your conveyancer handles the legal purchase and explains when you become committed.
A lender’s valuation is for its lending decision; it is not a substitute for a survey of the property’s condition. Legal purchase stages differ across the UK, particularly Scotland’s missives process. Take advice from your solicitor before making a binding commitment.
What if the AIP is declined or the amount is too low?
First check the information entered and ask what explanation the provider can give. An outcome might relate to affordability, credit history, identity matching or a lender’s policy on your circumstances. A referral for review is not necessarily a decline.
Do not change accurate figures to obtain a different answer. An adviser can help identify whether an error needs correcting, another lender’s criteria may be relevant or more preparation is needed. A decline by one provider does not establish what every lender will decide. If credit history is a concern, read our guide to preparing an AIP request with adverse credit.
Even after an AIP is accepted, the full application may result in a different amount or a decline. Income evidence, changes in circumstances, further credit information or the property’s valuation and suitability can affect the outcome.
Ask Count Ready whether an AIP is your next step
Tell us whether you are saving, viewing homes or preparing an offer, together with your approximate deposit, income and purchase budget. We can review your circumstances, explain relevant lender requirements and discuss whether an AIP is useful now.
Discuss my mortgage-in-principle options
Our enquiry form requests a conversation; it does not generate an AIP, submit a mortgage application or guarantee approval. You do not need to send identity documents or bank statements with the enquiry.
Advice is available by phone and online. Call 01245 934515. Let us know if you have owned a home before so we can discuss the relevant route.
The initial consultation is free. Fees for further work vary by case and are agreed before chargeable work begins. A processing fee may apply separately from an offer fee and is not charged in every case. Read our advice and fee explanation.
Your home may be repossessed if you do not keep up repayments on your mortgage.
Mortgage-in-principle questions
Are AIP, DIP and MIP the same thing?
Lenders commonly use agreement in principle, decision in principle and mortgage in principle for a provisional borrowing decision. Check the issuer and what assessment was completed, because a broker’s own estimate or certificate may work differently.
Do I have to use the lender that gave me the AIP?
An AIP does not normally commit you to taking that lender’s mortgage. You can review suitable alternatives before the full application. Another lender will carry out its own assessment, and any agreed broker fees should be checked separately.
How quickly can I get an AIP?
Some online processes return a decision quickly, but other cases need more information or manual review. The time depends on the provider, the accuracy of the details and your circumstances. Count Ready does not promise an instant decision.
Can I get an AIP if I am self-employed?
Potentially. The lender must be able to assess acceptable income for your business structure and circumstances. Use accurate figures and ask what supporting records will be needed; an initial result does not confirm that all income evidence has been accepted.
Can I make an offer for less than the AIP amount?
Yes. The figure is a provisional borrowing indication, not a spending target. Choose a price and mortgage payment you can afford while keeping enough for buying costs and other needs. The final lending decision still depends on the application and property.
Sources and related guidance
Checked on 7 September 2026 using MoneyHelper’s mortgage-in-principle guidance and Nationwide’s current DIP information linked above. Lender processes, periods and criteria can change.
For the wider deposit, costs and application process, read our first-time buyer mortgage guide. This page provides general information, not a personal mortgage recommendation.