Mortgage in Principle: what it is, what it checks, and what happens next

What is a mortgage in principle?

A mortgage in principle is a written indication of how much a lender might be prepared to lend based on a preliminary assessment. You give the lender or broker information about your income, regular spending, debts, deposit, address history, and intended purchase. The lender may also check your credit file.

Different lenders use different names and checks. An AIP from one lender cannot be assumed to represent the whole market, and the amount may change when supporting documents are reviewed. Treat it as a budget-planning step rather than approval.

Your home may be repossessed if you do not keep up repayments on your mortgage. This page is general information, not regulated mortgage advice.

What information do you need?

Have accurate figures ready before starting. A lender or broker will commonly ask for:

• your name, date of birth, nationality, and recent address history;
• employment status and gross income, including regular overtime, commission, bonuses, benefits, pension, or other income;
• self-employed trading history, accounts, SA302 tax calculations, and tax-year overviews where relevant;
• credit cards, loans, car finance, maintenance, childcare, and other committed spending;
• the deposit amount, where it came from, and whether any part is gifted or borrowed;
• the expected property price and whether it is a home, buy-to-let, new-build, flat, or specialist property.

The initial form may not request documents, but a full application will. Use the same figures throughout and correct any estimate before submitting a formal application. See the mortgage document checklist for a fuller preparation list.

Soft check or hard check?

MoneyHelper confirms that the credit-search type varies. A soft search is generally visible to you but not to other lenders as an application. A hard search is visible to other lenders and several hard applications in a short period can affect how your credit profile is assessed.

Do not assume every broker or lender uses a soft search. Ask explicitly before the check. If your credit history is complex, screening criteria before a hard application is particularly important. Read the bad-credit mortgage guide before applying repeatedly.

Mortgage in principle versus mortgage offer

Why can a full application still be declined?

An AIP can be followed by a decline or a lower loan amount when:

• documents do not support the income or spending figures entered;
• a hard credit check reveals information not considered initially;
• your job, income, debt, deposit, or credit position changes;
• the property valuation is lower than the agreed price;
• the property type, condition, lease, construction, occupancy, or title falls outside criteria;
• the lender changes its product or underwriting criteria before the full offer.

What should you do after receiving an AIP?

1. Set a purchase budget below the maximum if the repayments, fees, and emergency buffer would otherwise be uncomfortable.
2. Check the expiry date and avoid unnecessary repeat hard searches.
3. Keep your deposit traceable and avoid taking new credit before the full application.
4. When you find a property, tell the broker about its tenure, construction, occupancy, incentives, and any known defects before selecting a lender.
5. Prepare documents early and compare the total mortgage cost, not only the initial interest rate.

For the full journey, use the mortgage process timeline and repayment calculator.