Mortgage Arrangement Fees on Buy to Let

A buy-to-let mortgage's headline rate is only half the comparison. Arrangement fees (also called product fees or completion fees) vary hugely between deals, and a lower rate with a higher fee is not automatically cheaper than a higher rate with a lower fee once you look at the true cost over the whole fixed period.

This guide explains how to weigh fee against rate properly, what changes when a fee is added to the loan rather than paid upfront, and how to work out the genuine total cost of a deal over its fixed term.

Fee vs rate

Lenders generally offer a menu of product options on the same underlying mortgage, trading off the fee against the rate: a product with a larger arrangement fee usually carries a lower interest rate, and a product with little or no fee usually carries a higher rate. Neither option is inherently better; which one wins depends on the loan size and how long you intend to hold that specific deal.

The mechanics of why this trade-off exists are straightforward. A fee is a one-off, fixed cost regardless of loan size, while the rate is charged as a percentage of the loan every year of the fixed period. That means:

On a larger loan, a bigger fee is spread over more borrowed pounds, so it takes a smaller rate reduction to make the higher-fee product worthwhile.
On a smaller loan, the same fixed fee is a much larger proportion of the loan, so a lower-fee, higher-rate product is more likely to work out cheaper overall.
Over a longer fixed period, a one-off fee is spread over more years of interest savings, making higher-fee, lower-rate products relatively more attractive the longer you intend to hold the deal.

This is why the same lender, on the same day, will genuinely have different "best" products depending on whether the borrower has a £120,000 loan on a two-year fix or a £400,000 loan on a five-year fix. There is no single answer that applies across every case, which is exactly why comparing the total cost over the fix, not just the headline rate, matters.

Adding the fee to the loan

Most buy-to-let lenders let you add the arrangement fee to the mortgage balance rather than paying it upfront in cash. This is a common and often sensible choice, but it comes with a real trade-off that is worth understanding rather than treating as a free option:

You pay interest on the fee for the whole fixed period. Adding a fee to the loan means it is borrowed money like the rest of the mortgage, so you pay interest on it every month until the fix ends (and, if you never repay that portion, for as long as the wider loan continues).
It increases your loan-to-value. A fee added to the loan increases the total amount borrowed against the property's value, which can matter if you are close to an LTV threshold that affects your rate tier, or if the property's value has fallen since purchase.
It can affect rental cover. Because a lender's rental cover calculation is based on the size of the loan, adding the fee increases the loan slightly and therefore very slightly raises the rent needed to pass the stress test, though the effect of the fee itself is usually small compared with the effect of the interest rate.
Cash flow at completion is easier. The clear upside is that you are not finding several hundred, or in some cases over a thousand, pounds in cash on top of your deposit and other purchase costs at exactly the point your cash is most stretched.

Whether adding the fee to the loan is the right call depends on how much spare cash you have at completion versus how much the extra interest on the fee actually costs over the fix, which is easiest to see by comparing the true total cost calculation described below.

True cost over the fix

The only reliable way to compare two buy-to-let products fairly is to calculate the total cost of each over the specific period you intend to hold it, not just eyeball the rate and fee side by side. The calculation has three components:

Total interest over the fixed period, using the product's rate applied to the loan amount (including the fee, if you plan to add it to the loan) for each year of the fix.
The arrangement fee itself, added once, whether paid upfront or added to the loan.
Any other product-specific costs, such as a valuation fee, that differ between the products being compared.

Worked example

A landlord is comparing two five-year fixed products on a £200,000 loan:

Product A: 4.5% rate, £1,999 fee
Product B: 4.7% rate, £499 fee

Over five years, ignoring compounding for simplicity: Product A's interest is roughly £200,000 x 4.5% x 5 = £45,000, plus the £1,999 fee, for a total of about £46,999. Product B's interest is roughly £200,000 x 4.7% x 5 = £47,000, plus the £499 fee, for a total of about £47,499. On this loan size and this fixed period, Product A is cheaper overall by around £500, despite having the much larger headline fee, purely because the 0.2 percentage point rate saving over five years outweighs the extra £1,500 in upfront fee.

Run the same comparison on a smaller loan, say £80,000, and the result flips: the rate saving on Product A (0.2% of £80,000 x 5 years, around £800) barely covers the extra £1,500 fee gap, making Product B the cheaper option on that loan size over the same five-year term. This is exactly why fee-versus-rate decisions cannot be generalised; they depend on your specific loan amount and intended term.

Comparing deals properly

When shortlisting buy-to-let products, work out the total cost over your actual intended fixed period for every product on the shortlist, not just the two extremes. A broker can usually run this calculation quickly across a wider range of lenders than most landlords would compare manually, which is one of the clearer, concrete ways a broker earns their fee on a straightforward case. Our guides on how buy-to-let mortgages work and remortgaging a buy-to-let cover the wider decision around rate type and timing that sits alongside the fee comparison.

Property HQ tracks the mortgage details for every property in your portfolio, including rate and fixed-rate end date, so when a renewal comes round you already have your current deal's true numbers to hand as the benchmark for comparing whatever comes next.

Disclaimer

This guide is general information for UK landlords, not mortgage advice. Rates, fees and product terms vary by lender and change frequently - get current, personalised figures from a broker or lender before making a borrowing decision.