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AIP vs mortgage offer (UK): what’s the difference?

An AIP/DIP is an early borrowing indication; a mortgage offer is the lender’s formal offer for a specific property after full checks. Here’s the practical difference.

Published: 12/05/2026 • Last verified: 12/05/2026

The short answer

An AIP (agreement in principle) is an early indication of how much a lender might lend, based on limited information. It’s useful for budgeting, but it’s not the same as an approval for a specific property.

A mortgage offer is the lender’s formal offer for a particular property after a full application and checks. Offers can be conditional (for example, subject to documents, confirmations, or the lender being happy with the valuation).

A tiny example

You get an AIP for £250,000 based on your income and an initial affordability check.

Later, you apply for a mortgage on a specific home:

  • The lender reviews bank statements and employment details.
  • A valuation is carried out.

If the valuation comes back lower than the agreed price (a “downvaluation”), or the lender’s checks show different outgoings than expected, the lender may:

  • Offer less than £250,000, or
  • Offer the same amount but with conditions, or
  • Decline the application.

That’s why an AIP is best thought of as a starting point, not the finish line.

FAQ
Does an AIP guarantee I’ll get a mortgage offer?
No. An AIP is an early indication. A full application can still be declined after detailed checks and (often) a valuation.
Do I need an AIP before viewing houses?
Not always, but many buyers get one early because it helps set a budget and can make offers look more credible.
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