Santander Interest Only Mortgage Criteria 2026

Interest‑only lending has become increasingly relevant again, especially for high‑earning professionals and clients with strong assets behind them. Santander interest only mortgage criteria are detailed, specific, and often misunderstood, which is why this 2026 guide breaks everything down clearly for borrowers and advisers.

Below is an up‑to‑date explanation of Santander’s full interest‑only policy, helping you understand the rules before applying.

Maximum Age & Term Rules for Santander Interest Only Mortgage Criteria

Santander Interest Only Mortgage criteria around age is strict and non‑negotiable:

• The oldest applicant must not exceed age 70 at the end of any interest‑only loan part.
• Maximum mortgage term: 40 years.
• For part‑and‑part mortgages, no loan part can exceed the interest‑only term.

Existing Santander customers with interest‑only already in place can port their deal, subject to meeting current criteria.

Acceptable Repayment Vehicles for Santander Interest Only Mortgage Criteria

Santander only accepts a very limited list of repayment strategies. These must be evidenced at application stage and remain plausible throughout the mortgage term.

1. Sale of the Mortgaged Property

This is the most common route.

Requirements:

• Minimum £300,000 equity in the property at the end of the term
• Confirmation of the client’s future plans after selling the property
• If the plan is to buy another residential property and the term is under 10 years, Santander requires details of:
  • Location
  • Type
  • Size

Documentation:

• “Interest Only – Sale of Mortgaged Property Customer Declaration” must be completed and uploaded at application
• Evidence must be retained on file for 2 years

Santander may request additional information at any time to check plausibility.

2. Investment Vehicles accepted by Santander Interest Only Mortgage Criteria

These must be FCA‑regulated, held for at least 12 months, and owned by the same applicants on the mortgage.

Santander accepts:

Mortgage‑related Endowments or Mortgage‑related ISAs

• Use the mid‑point projection at maturity
• Latest annual statement (within 15 months)

Investment Portfolios

Includes:

• Shares
• Unit trusts
• OEICs
• Investment bonds

Requirements:

• Use current cash value only
• Latest statement (within 12 months)
• No growth projections allowed
• Clients must not have reduced their holdings since the last statement

Not accepted under any circumstances:

• Pensions
• Sale of other properties (including BTLs)
• Bonuses
• Overpayments
• Cash savings (including Cash ISAs)
• Inheritance

Income Requirements & Maximum Income Multiples

Santander Interest Only Mortgage criteria around income is one of the most important parts of their policy.

Minimum Income

• No minimum income required for interest‑only
• But income multiples vary depending on combined gross income:

Income can include primary and secondary sources, but must be fully evidenced.

Loan‑to‑Value (LTV) Rules for Santander Interest Only Mortgage Criteria

Santander applies different LTV caps depending on income level:

• Maximum overall LTV: 85%
• If income is £200,000+, any borrowing above 75% LTV must be on capital & interest
• If income is below £200,000, any borrowing above 50% LTV must be on capital & interest

Affordability is always assessed on a capital & interest basis, even if the loan is part interest‑only.

Existing Santander Interest‑Only Borrowers

Santander may consider applications where the existing repayment vehicle is no longer acceptable, but only if:

• No increase in the interest‑only loan part
• LTV does not increase
• Term does not increase
• Maximum age does not exceed 75
• Maximum LTV remains 85%

This applies only when the existing mortgage is redeemed simultaneously.

Is Santander a Good Option for Interest‑Only Borrowers?

Santander can be an excellent choice for:

• High earners
• Clients with strong equity
• Borrowers with robust investment portfolios
• Those planning to downsize with significant equity

However, their rules are strict, and applications must be packaged correctly to avoid delays or declines.

Thinking About an Interest‑Only Mortgage?

Interest‑only lending is becoming more popular — and with the right structure, it can unlock significantly higher borrowing for the right clients.

At MDJ Mortgages, we specialise in:

• High‑income borrowers
• Complex income structures
• Interest‑only and part‑and‑part lending
• Repayment vehicle assessment
• Lender‑specific packaging to maximise approval chances

If you’d like a full‑market interest‑only review, tailored to your income, assets, and long‑term plans, we’d be happy to help.

Contact us today to explore your options.

Risk Warning

Your home may be repossessed if you do not keep up repayments on your mortgage.

You may have to pay an early repayment charge to your existing lender if you remortgage.

This information is specific to Santander and there are other lenders available