How to get an interest-only investment mortgage (buy-to-let)

An interest-only investment mortgage is designed for landlords and property investors who want to keep monthly payments lower by paying only the interest during the mortgage term. Instead of repaying the loan balance as you go, you plan to clear the outstanding capital at the end of the term.

For many investors, this can be a useful structure—particularly where rental income is expected to cover the ongoing cost of borrowing, and where the capital repayment is expected to come from a sale, refinancing, or another pre-planned source.

What is an interest-only investment mortgage?

With an interest-only mortgage, your monthly payment is based on the interest charged on the loan. The capital (the original borrowing amount) is not reduced in the same way as with a capital repayment mortgage.

An interest-only investment mortgage applies this approach to investment property lending. That means the lender will focus heavily on how the loan will be repaid at the end of the term, because there is no automatic reduction of the balance through monthly capital repayments.

In practice, you'll need a credible repayment plan for the outstanding capital—whether that's selling the property, using savings, using inheritance, or refinancing.

Why investors choose interest-only for investment property

Landlords and investors often consider interest-only because it can:

• Reduce monthly outgoings compared with repayment mortgages
• Improve cashflow where rental income is intended to cover interest costs
• Support a strategy where profit is expected from rental income, capital growth, or both
• Help with portfolio planning where keeping payments manageable supports further investment

That said, interest-only lending can carry added risk if the repayment strategy doesn't work out as expected—particularly if property values fall or refinancing becomes harder.

Interest-only vs repayment: what's the difference?

Repayment mortgages are designed so that your monthly payments gradually reduce both the interest and the capital. By the end of the term, the mortgage is usually paid off.

Interest-only mortgages focus on affordability during the term, but the capital repayment is deferred. This can suit certain landlord circumstances—provided the repayment plan is robust.

A third option is a part and part mortgage—a split between interest-only and repayment—where some of the capital reduces over time while a portion is deferred to the end of the term. This can offer a middle ground between lower payments and gradual capital reduction.

Types of interest-only investment mortgages

Interest-only structures can appear across several categories of investment property finance. Depending on the property type, lenders may apply different rules around risk, affordability and loan-to-value.

Buy-to-let mortgages

For standard buy-to-let, the lender will typically look at whether the rental income is likely to cover the mortgage payments and whether the overall lending risk is acceptable.

HMO mortgages

HMO (house in multiple occupation) lending can be more complex because of the property's layout, management considerations and tenant turnover. Interest-only options may be available, but criteria can be stricter.

Holiday let mortgages

Holiday let lending is often treated differently from long-term residential letting. Lenders may consider factors such as the property's location, expected income pattern and how the holiday rental business is evidenced.

Commercial mortgages

Some commercial property lending can be interest-only, especially where income may fluctuate or where the borrower's repayment plan is linked to business performance.

Buy-to-renovate mortgages

Where a borrower is funding purchase and renovation, interest-only structures may be considered in certain cases—particularly where the repayment plan relies on the property's improved value after works.

How lenders assess an interest-only investment mortgage

While each lender has its own approach, most will focus on a few core areas. Understanding these helps you prepare the right information and repayment narrative.

1) Loan-to-value (LTV)

Interest-only investment mortgages often require a deposit. LTV limits vary by lender and property type, and can be lower for higher-risk categories. Interest-only lending may be more sensitive to LTV than repayment mortgages.

2) Repayment strategy for the capital

This is one of the most important elements. Lenders will want to understand how you intend to clear the outstanding balance at the end of the term.

A strong repayment plan is usually clearer, more realistic and better evidenced. Common approaches include:

• Sale of the property at (or before) the end of the term
• Refinancing (where the lender expects the property to remain financeable)
• Use of savings or other funds
• Other planned sources (for example, inheritance), where appropriate evidence can be provided

It's important that the plan is realistic and aligns with the mortgage term you're applying for. Where investments are involved, lenders may look for evidence that the plan is realistic—not just theoretically possible.

3) Rental income and affordability (investment-focused)

For buy-to-let and many investment mortgages, lenders typically assess whether the rental income is sufficient to cover the mortgage payments, alongside other commitments.

Even where interest-only reduces monthly capital pressure, lenders still need confidence that the investment can support the ongoing cost of borrowing.

4) Property and risk considerations

Lenders may consider the property's type, location, condition, and how it fits within their lending policy.

For example, HMOs and holiday lets can involve different risk profiles and may require additional evidence of income potential or management arrangements.

5) Borrower background and experience

Some lenders place more weight on borrower experience—particularly for niche property types—while others may focus more on the strength of the repayment plan and the investment's income.

6) Your overall financial position

Lenders may review wider circumstances such as existing borrowing, credit history, and stability of income.

Preparing to apply: what to have ready

Interest-only investment lending tends to reward preparation. While requirements vary, it's helpful to gather:

• Details of the property (including type and intended use)
• Evidence supporting rental income (where available) and how it was calculated
• Your repayment plan for the capital at the end of the term
• Information about your deposit and overall financial position
• Any relevant documentation for the investment strategy (especially for HMOs, holiday lets or renovation plans)

Let-to-buy and interest-only structures

Let-to-buy is where you convert your current home into an investment property and buy a new home, often resulting in two mortgages.

In some situations, both mortgages may be structured on an interest-only basis. Lenders will generally want to see that you can manage both commitments and that the equity in your existing home supports the new purchase.

Alternatives to interest-only investment mortgages

If interest-only doesn't fit your strategy, other options may include:

• Capital repayment buy-to-let mortgages: higher monthly payments, but the loan balance reduces over time
• Part and part mortgages: a split between interest-only and repayment, balancing lower payments with gradual capital reduction
• Different term lengths to better align with your investment horizon
• Bridging finance: short-term funding where you expect a quicker exit or refinancing
• Development finance: where the investment is tied to building or renovation
• Equity release or second charge lending: depending on your circumstances and property value
• Other borrowing structures: such as personal or business loans, where appropriate

Key risks to consider

Interest-only investment mortgages can be attractive, but they rely on the success of the repayment plan. Common risks include:

• End-of-term capital risk: The biggest risk is that the capital may not be fully covered when the mortgage ends—particularly if property values fall, investment returns are lower than anticipated, or costs reduce your ability to contribute to the repayment plan.
• Interest rate and affordability pressure: Even if the mortgage is interest-only, the monthly interest cost can still change depending on the product type. If rates rise, rental income may not fully offset the increased interest.
• Rental income uncertainty: Buy-to-let cashflow isn't guaranteed. Voids, repairs, insurance, and compliance costs can all affect net income.
• Repayment vehicle performance: If you're relying on an investment or savings vehicle, performance is not guaranteed.

A clear strategy and realistic assumptions can make a meaningful difference when lenders review your application.

If you can't repay the capital at the end

If the repayment plan doesn't fully work out, there may be options to manage the situation, but they can involve trade-offs. Potential approaches landlords may consider include:

• Switching to a repayment structure to reduce the remaining balance over time (generally increasing monthly payments)
• Extending the term or adjusting the repayment approach, where available
• Making up a shortfall using savings or other funds
• Selling the property to clear the outstanding debt (which may depend on market conditions and timing)

The important point is that interest-only mortgages require contingency planning. Knowing what you would do if values or returns are lower can be as valuable as the original plan.

Summary

To get an interest-only investment mortgage, you typically need more than just a deposit. Lenders will usually place significant emphasis on:

• your loan-to-value
• your capital repayment strategy
• the ability of the investment to support the ongoing mortgage payments
• the property type and associated risk

If you're considering interest-only for a buy-to-let or other investment property, building a well-evidenced repayment plan and understanding how different lenders view risk can help you approach the market with confidence.

Important note

A buy-to-let mortgage arranged on an interest-only basis means you will not make repayments towards the capital during the term. You must ensure you have a suitable repayment plan in place to clear the full balance at the end of the agreed term.

Your property may be repossessed if you do not keep up repayments on a mortgage or other loan secured on it.