Mortgage in principle in the UK: what to know first

What it is, and what I could not confirm

Estate agents and sellers often ask for a mortgage in principle before taking an offer seriously. Typically it is based on the details you give about income, spending and the amount you want to borrow, sometimes with a credit check.

I looked for an official UK source (FCA, GOV.UK, the devolved governments) defining the term, its validity period and the type of credit check used, and did not find one. These points therefore depend on the lender, and you should ask it directly:

• Is the credit search a soft search or a hard search that other lenders can see?
• How long does the indication last?
• What exactly does it assume about your income and the property?
• Does it carry any fee?

The in-principle document is not a regulated mortgage offer. The lender’s final decision follows a full application and the checks below.

What the lender must do at full application

The FCA rules in MCOB 11.6 apply to the full application, in every nation of the UK.

• The lender must obtain evidence of the income you declare and must not accept self-certification of income (MCOB 11.6.8R).
• It must not rely on a general declaration of affordability from you (MCOB 11.6.6R).
• It must take reasonable steps to find your actual outstanding commitments (MCOB 11.6.12R).
• It must consider likely interest rates over at least five years and assume a rise of at least 1%, unless your rate is fixed for that period or for the whole term if shorter (MCOB 11.6.18R).
• It must not base the assessment on equity in the property (MCOB 11.6.5R).

So a quick figure based on what you typed in can be higher than what the lender offers after it has seen payslips and bank statements. See mortgage affordability rules for the detail.

What to prepare

Your lender or adviser will tell you what it needs, but expect to gather:

• proof of identity and address;
• recent payslips or, if self-employed, the income evidence the lender asks for;
• bank statements showing income and regular spending;
• a list of debts and monthly payments;
• the source of your deposit, including any Lifetime ISA (see the Lifetime ISA guide, where a conveyancer or solicitor must act and the mortgage conditions apply).

How it fits into buying in each nation

The buying process differs by nation, which affects when you need your finance in place. For Scotland, mygov.scot describes a legal process made of the Home Report, making an offer, conveyancing and settlement: speak to a solicitor about timing before you bid. See buying a home in Scotland and buying a home in England. The lender’s affordability duties are the same in all four nations.

How much to look for

The ONS reports an average loan-to-income ratio of 3.6 for first-time buyers in 2025, and a median loan-to-value of 85.6%. These are averages of what people did, not limits. Your own figure depends on income, debts and the lender.

Which professional to consult

A mortgage adviser can obtain several indications in principle and explain which type of credit check each lender uses; see the mortgage adviser page. Check that the firm is authorised on the FCA register yourself. A conveyancer should be instructed once your offer is accepted; see the conveyancer page.