Mortgage in principle vs full application: the differences

A mortgage in principle is a calculation based on what you say about yourself. A full application is an investigation into whether what you said is true, whether the property is worth what you are paying, and whether the lender wants this specific risk. The first takes minutes and commits nobody. The second usually takes two to five weeks, involves an underwriter reading your bank statements and a valuer inspecting the property, and ends in a binding formal mortgage offer.

Three things happen that did not happen before. Your declared information gets verified against documents. The property gets valued. And a human underwriter applies judgement to the parts of your case a calculator cannot see.

That third element is the one people underestimate. An automated engine asks whether the numbers fit the policy. An underwriter asks whether the story makes sense: why your income jumped 40 percent last year, why there is a 3,000 pound transfer from an account nobody has mentioned, why you are moving from a permanent role to a contract two weeks before completion.

The application also attaches an actual product. Until this point no rate has been reserved. At full application you select the product, the rate is secured to that case, and the product fee is either paid or added to the loan.

Expect to supply, in roughly this order:

• Photographic identification and proof of address
• Three months of payslips and often the most recent P60 if you are employed
• Two to three years of tax calculations and tax year overviews, or accountant-certified accounts, if you are self-employed
• Three to six months of bank statements for your main current account
• Evidence of the deposit and its source, including a gift letter where relevant
• Proof of any additional income such as bonus, commission, overtime or benefits

Bank statements get the closest reading. Underwriters look for regular gambling, undeclared loan repayments, returned direct debits, unauthorised overdraft use, buy now pay later commitments and any credit that appears without explanation. None of these is automatically fatal, but each one you have not flagged in advance becomes a question, and questions cost days.

The mismatch that causes most trouble is income. If you rounded your salary up at the mortgage in principle stage, or included a bonus the lender will only count at 50 percent, the verified figure comes back lower and the borrowing figure falls with it.

The lender instructs a valuation to protect its own security, not to advise you on the condition of the house. It may be a desktop valuation using data alone, a drive-by external inspection, or a full internal inspection, depending on the lender, the loan to value and the property type.

Three outcomes are possible. The valuer agrees the price, which is the usual result. The valuer reports the property as worth less than you are paying, which is a downvaluation. Or the valuer flags the property as unsuitable security altogether, for example because of a short lease, structural movement, cladding concerns, spray foam insulation in the loft, or a non-standard construction the lender does not lend on.

A downvaluation is the single most common reason an application fails after a positive mortgage in principle. If a lender values a property at 285,000 pounds when you have agreed 300,000 pounds with a 45,000 pound deposit, the lender lends against the lower figure. At 85 percent of 285,000 pounds that is 242,250 pounds, so you need 57,750 pounds rather than 45,000 pounds. Your options are to find the difference, renegotiate the price, challenge the valuation with evidence of comparable sales, or try a different lender who may instruct a different valuer.

Remember the lender's valuation is not a survey. If you want to know about the roof, commission your own level two or level three survey. Costs vary by property size and region, but a homebuyer level report commonly runs into several hundred pounds and a full building survey more than that.

The recurring causes are consistent and largely preventable:

• A downvaluation, as above
• Credit commitments that were not declared, including car finance and buy now pay later balances
• A change of employment, particularly moving to a new job with a probation period, or from employed to self-employed
• Bank statement entries the applicant cannot explain
• New credit applied for during the process, such as a loan for furniture or a new card
• Adverse credit appearing on the file that the applicant did not know about
• The property itself being unacceptable security

A lender can withdraw at any point before completion, including after a formal offer has been issued. That is rare, but it happens, most often when the lender is told about a material change or discovers something new.

From submission to formal offer, two to five weeks is typical. Straightforward employed cases with everything supplied up front can be quicker. Self-employed cases, cases with adverse credit, new builds and leasehold flats tend to be slower.

The valuation is usually instructed within a few days of submission and carried out within a week or two, though this varies with local surveyor availability. Underwriting happens in parallel or immediately afterwards. Requests for further information, known as further conditions, are normal and are not a sign of trouble.

The formal mortgage offer, once issued, usually lasts around three to six months. That is the clock that then governs your purchase.

Prepare before you submit, not after you are asked.

• Pull your own credit reports from more than one agency and check for errors before applying
• Declare every commitment, including the small ones
• Do not apply for any new credit between application and completion
• Do not change jobs during the process if you can avoid it, and tell your broker immediately if you must
• Write a short note explaining any unusual transaction on your statements and supply it up front
• Keep at least six months of statements, payslips and deposit evidence in one folder
• Answer lender queries the same day where you can, because cases sit in a queue and each round trip costs time

A decline is not the end. Ask for the reason. If it is a downvaluation, you have four routes as described above. If it is criteria, a different lender may take a completely different view of the same case, particularly on contract income, recent adverse credit or unusual property types.

What you should not do is fire off applications to three more lenders at speed. Each one adds a credit footprint and none of them will look better than the last if the underlying issue is unresolved. Diagnose first, then apply once, to a lender chosen because its criteria fit.

Brokers who deal with the same underwriters weekly tend to know which lender will take which case. You can search the MortgageMatch directory for FCA-authorised brokers and compare their experience with cases like yours before you commit.