The interest rate is usually the first number a landlord looks at when comparing mortgages. That is understandable: it directly affects the monthly payment and the income left over from the property.

But the rate tells only part of the story.

A mortgage with a lower rate can cost more once fees are included. It may also release less capital, restrict future plans or become expensive to exit. The right comparison starts with the property, the borrowing required and what the landlord intends to do next.

A lower rate can come with a higher fee

Buy-to-let products often offer a choice between a lower interest rate with a larger arrangement fee and a higher rate with a smaller fee.

Where the fee is a percentage of the borrowing, the difference can be substantial.

Take a simplified example of two interest-only mortgages on a £300,000 loan. One charges 4.5% with a 5% arrangement fee. The other charges 5% with a 2% fee.

The lower rate saves £1,500 a year in interest. But its arrangement fee is £9,000 higher. Over a two-year period, that means paying £9,000 more to save £3,000.

These are illustrative figures, assuming fees are paid upfront and all other costs are equal. They show why comparing the monthly payment alone can produce the wrong conclusion.

A higher fee is not automatically poor value. It needs to earn its place through sufficient savings or another benefit that matters to the borrower.

Adding the fee does not remove the cost

Adding an arrangement fee to the mortgage can preserve cash for refurbishment, another purchase or unexpected expenditure.

But the fee remains a cost. It increases the mortgage balance and, where interest is charged on it, the amount paid over time.

For an interest-only borrower, that additional balance generally remains outstanding unless it is repaid separately. A product can therefore appear attractive in monthly cash-flow terms while leaving a larger debt at the end of the initial deal.

We need to distinguish between keeping the monthly payment low, preserving cash today and minimising the overall cost. Those objectives do not always point to the same mortgage.

The lender’s rental calculation affects the structure

The amount a landlord can borrow is not determined by the property value alone.

Lenders also assess whether the rent sufficiently covers the mortgage interest under their affordability calculation. Their approach can vary according to the product, fixed-rate period, ownership structure and borrower’s circumstances.

That can make a meaningful difference to the capital required.

A competitively priced mortgage may leave a landlord needing to contribute substantially more cash. Another lender may support the required borrowing, allowing the landlord to retain reserves or complete planned works.

Borrowing more is not inherently better. But comparing mortgages without considering the cash contribution each requires gives an incomplete picture.

The expected holding period matters

A mortgage needs to fit the period for which the landlord realistically expects to keep it.

Someone holding a completed investment for the long term may value payment certainty. Someone planning to refurbish, sell, split titles or refinance after an increase in value may need greater flexibility.

Early repayment charges can outweigh an initial rate saving if the mortgage needs to be redeemed sooner than expected.

The question is therefore not simply how long to fix for. It is what could happen to the property during that period, and whether the mortgage accommodates those plans.

The mortgage must fit the property’s use

A low rate has little value if the product does not permit the way the property will be occupied.

Holiday letting, corporate lets, HMOs and other specialist arrangements can require different lending terms. A landlord may also intend to change the letting model once refurbishment or other works are complete.

That intended use needs to be understood at the outset.

Otherwise, a mortgage chosen for its initial pricing could lead to another application, further fees and potentially an early repayment charge when the landlord is ready to proceed with the next stage.

Portfolio decisions extend beyond one property

For landlords with several properties, the cheapest mortgage on an individual asset may not produce the most useful arrangement across the portfolio.

Separate mortgages can provide flexibility to sell or refinance properties individually. A facility secured across several properties may suit other objectives, but its terms for releasing an individual property need careful consideration.

Refinancing dates also matter. Several deals expiring together can create a concentrated funding requirement, while repeated short deals can bring recurring arrangement, valuation and legal costs.

Each mortgage decision should therefore be considered alongside the landlord’s wider borrowing and investment plans.

Start with the plan, then compare the price

At Pavilion, we begin by understanding what the borrowing needs to achieve.

How much capital is required? What cash should remain available? How will the property be used? Is a sale, refurbishment or further refinance likely?

We then compare the cost over a relevant period, including fees, interest, any exit charges and the balance that will remain outstanding.

Sometimes the lowest rate is also the best fit. Sometimes paying a slightly higher rate produces a lower overall cost or gives the landlord flexibility that is worth considerably more.

The aim is to choose a mortgage that remains appropriate after the first monthly payment.