Viewing homes before you know your budget wastes time and sets you up for disappointment.
That is a costly mistake. You may spend weeks looking at properties out of your price range. Or you make an offer and find out the numbers do not work.
A mortgage in principle (MIP) estimates how much you can borrow.
It is free. It takes under ten minutes to complete. And it shows sellers and estate agents that your offer carries real weight.
This blog covers what a mortgage in principle is and what lenders check. You will also learn how to get one and what to do if the figure is lower than expected.
What Does a Mortgage in Principle Mean?
A mortgage in principle is a written estimate from a lender showing the maximum they may be willing to lend. It is based on a basic financial review.
It is not binding like a mortgage deed. You are free to apply with any lender after receiving it.
- Also called an Agreement in Principle (AIP), Decision in Principle (DIP), or Mortgage Promise.
- It gives you an early indication of your borrowing limit before you start searching.
- It is not binding. You can apply with any lender after receiving it.
- A full mortgage application still involves more detailed checks before a final decision is made
A mortgage calculator provides an estimate based on inputs. A mortgage in principle involves lender verification, making the figure more credible for sellers and agents.
What Does a Mortgage in Principle Check?
When you apply for a mortgage in principle, a lender checks your earnings, debts, deposit size, and credit history. These details help them estimate your borrowing capacity.
1. Income and Employment Details
Your income is the first thing a lender checks. They want to know how much you earn and how stable that income is. Employment type matters too.
- Salary: Full-time or part-time income, including regular bonuses.
- Self-employed earnings: Lenders typically review your last two years of accounts or tax returns.
- Other income sources: Rental income, investment returns, or regular benefits may also count toward your total.
2. Monthly Outgoings and Existing Debts
Lenders do not just look at what you earn. They also check how much you spend each month. High outgoings reduce the amount they may offer.
- Bills: Regular household costs, including utilities, insurance, and subscriptions.
- Loans: Outstanding personal loans or car finance repayments in your name.
- Credit cards: Both existing balances and minimum monthly payments are factored into the calculation.
3. Deposit and Property Details
The size of your deposit and your target property value directly affect what a lender may offer. A larger deposit typically improves your borrowing options.
- Planned deposit: The amount you intend to put down. A larger deposit usually gives you access to better rates and a higher loan amount.
- Property value: The price range you are targeting. Lenders use this to work out your loan-to-value (LTV) ratio, which shapes what they are willing to lend.
4. Credit History and Address History
Your credit history shows lenders how you have handled borrowing in the past. Your address history helps verify your identity. Both are checked at the MIP stage.
- Credit behavior: Missed payments, defaults, or County Court Judgments (CCJs) can reduce the amount offered or result in a refusal.
- Three years of address history: Lenders use this to run credit checks and confirm you identity. Have all previous addresses ready before you apply.
5. Soft Check vs. Hard Check: Which Does Your Lender Use?
Most lenders run a soft credit check for a mortgage in principle, though a few still use a hard check instead. Choosing a lender that runs a soft check can help protect your credit score while you compare mortgage options. Here’s a quick comparison to help you understand the difference.
| Feature | Soft Credit Check | Hard Credit Check |
|---|---|---|
| Visibility | Not visible to other lenders | Visible on your credit file |
| Credit Score | No impact | May slightly lower your score |
| MIP Stage Use | Used by most lenders | Some lenders still use it |
Pro Tip: Always ask your lender which type they run before you submit your application. This matches guidance from MoneyHelper, the UK’s government-backed money advice service.
How Do You Get a Mortgage in Principle?
You get a mortgage in principle in four quick steps, most of it done online in under 10 minutes. Have a few financial details ready before you start.
Here are the four steps to follow.
- Gather your details: Income, monthly outgoings, deposit amount, and three years of address history.
- Choose your route: Apply online directly with a lender, by phone, or through a mortgage broker.
- Submit your application: Provide accurate information; errors can delay or affect the result.
- Get your decision: Most lenders give an instant result during business hours.
What is a Mortgage in Principle Used For?
A mortgage in principle is used to set your budget, prove to sellers you are a serious buyer, and speed up your property search. Here is how buyers put it to use.
- Set your budget. Knowing your monthly repayments before you start helps you focus on the right price range.
- Show sellers you are serious. Sellers take offers more seriously when a lender has already reviewed your finances.
- Strengthen your position in a competitive market; an MIP puts you ahead of buyers who do not have one.
- First-time buyers are particularly useful since you have no property to sell as evidence of funds.
This matters most for first-time buyers, since you have no property sale to prove you have funds ready. Agents and sellers tend to move faster on offers from buyers who already have an MIP.
What Happens If Your Mortgage-in-Principle Comes Back Low?
A low mortgage in principle means something in your finances needs fixing, usually existing debt, income type, or credit history, before a full application.
Here are the most common causes and your next steps.
Common reasons it comes back low:
If your mortgage in principle is lower than expected, one or more factors may be reducing your borrowing amount.
- High credit card balances or existing loan repayments.
- Variable or self-employed income that lenders calculate conservatively.
- A deposit below the lender’s required minimum threshold.
- Recent missed or late payments recorded on your credit file.
What to do next:
If your MIP is lower than expected, these simple steps may help improve your borrowing amount.
- Check your credit report for errors and request corrections.
- Pay down existing debts before you reapply.
- Try a different lender. Comparing specialist lenders can make a real difference to your final figure.
- Speak to a mortgage broker who knows which lenders fit your profile, including buyers looking at a semi-commercial mortgage.
What Can Stop Your Full Mortgage After an MIP?
Property issues, financial changes, or a failed hard credit check can all stop your mortgage from closing after an MIP. Lenders run much deeper checks at that stage.
Here are the most common reasons a full application gets declined after an MIP approval.
- Lenders can refuse property types based on condition, such as high-rise flats above certain floors, homes lacking working kitchens or bathrooms, or non-standard construction.
- Changes in your finances, such as a new loan, reduced income, or extra debt taken out after your MIP, can change the lender’s decision.
- The full credit check, the hard check at the full application stage, may reveal issues the soft MIP check did not.
- Lender criteria change as the lenders can adjust their internal rules between your MIP and your full application date.
Key point: Once a lender sends you a mortgage illustration, it is a strong sign your full application is moving forward.
How Long Does a Mortgage in Principle Last?
A mortgage in principle has an expiry date. Most last between 30 and 90 days. If yours runs out before you make an offer, you can usually renew it without starting from scratch.
| Lender | MIP Validity |
|---|---|
| NatWest | 30 days |
| Halifax | 30–90 days |
| Nationwide | 90 days |
Lender terms change. Confirm current validity directly with your lender before relying on these figures.
- Check whether renewing your MIP triggers another credit check before you request one.
- If your income or outgoings have changed since your original MIP, apply for a fresh one rather than renewing.
- A lapsed MIP does not erase your original approval; renewals are usually straightforward.
Conclusion
A mortgage in principle is one of the simplest steps you can take before buying a home.
It gives you a real number to work with. It gives sellers confidence in your offer. And it sets your property search in the right direction.
Getting one before viewing homes saves time and keeps you focused on properties within your budget.
If the figure comes back lower than expected, you now know what to fix first. The biggest mistake buyers make is skipping this step.
It costs nothing, and most lenders give you a decision in under 10 minutes. Do you have a question about your situation? Leave it in the comments.
Frequently Asked Questions
What Should You Not Tell Your Mortgage Lender?
Never misrepresent your income, hide existing debts, or lie about how you plan to use the property. Lenders verify everything.
Do You Need a Mortgage-in-Principle Before Viewing a House?
No, it is not a legal requirement. But many estate agents ask for one before booking viewings, especially in a competitive market.
Can You Get More Than One Mortgage in Principle?
Yes. Having one MIP does not stop you from getting another from a different lender if your first figure falls short.
Do I Have to Tell the Estate Agent My Exact Mortgage-in-Principle Amount?
No. You can share your mortgage in principle to prove you’re funded without disclosing the exact figure, which can help protect your negotiating position.
How Many Times Can I Apply for a Mortgage in Principle?
As many as you like with a soft-check lender. Repeated hard credit checks within a short period can lower your credit score, so confirm which type of credit check your lender uses first.
