BTL Remortgaging in 2026: How to Stress-Test Your Deal

Around 1.8 million fixed-rate mortgages expire in 2026. Roughly £49.7 billion of those are buy-to-let loans. Many of the landlords rolling off those deals are finding that the rate they are being quoted is not the only problem.

The other problem is the lender saying: "Your rental income no longer covers the affordability test."

A significant share of those maturing BTL deals were fixed in 2021 at rates between 2% and 3%, when the Bank of England base rate sat at 0.1%. Today, the average two-year BTL fixed rate stands at 5.46% and the average five-year fix at 5.77% (Moneyfacts, 9 April 2026). That gap, from where landlords were to where they need to be, is what is driving the problem. And the mechanism behind the "your rent doesn't cover it" message is something called the ICR stress test.

This article explains exactly how that test works, walks through the maths with clear examples, and covers what your options are if your property is failing it.

What is ICR and Why Does It Matter?

ICR stands for Interest Cover Ratio. It is the calculation lenders use to decide whether a buy-to-let property generates enough rental income to support the mortgage, even if interest rates rise after you take it out.

Critically, lenders do not test against the rate on the product they are offering you. They test against a minimum stress rate, sometimes called a floor rate. That floor rate is typically 5.5% across mainstream and specialist BTL lenders in 2026. The logic is straightforward. If you take out a five-year fix at 4.5% and rates spike in year three, can your rent still cover the payments? The stress test is designed to answer that before you borrow.

On top of the stress rate, lenders apply an ICR threshold. The amount your rent must exceed the stressed interest, expressed as a percentage. The standard requirements in 2026:

• 125% ICR for basic-rate taxpayers and limited company borrowers
• 145% ICR for higher-rate taxpayers owning property in personal name

Portfolio landlords, those with four or more mortgaged buy-to-let properties, face stress testing across their entire portfolio, not just the property being remortgaged. One underperforming property in the background can affect your ability to secure finance on a different asset. For more on that, see Portfolio Landlord Rules Explained.

These requirements originate from the Prudential Regulation Authority's Supervisory Statement SS13/16, reinforced by Policy Statement PS1/26 published in January 2026 and effective from January 2027.

Where Rates Are Now

As of 9 April 2026, Moneyfacts data shows:

• BTL two-year fixed average: 5.46%
• BTL five-year fixed average: 5.77%

Both figures are at their highest level in roughly two years. The fact that five-year fixes sit above two-year deals is unusual. It reflects lender caution about medium-term rate direction, with SWAP rates elevated and the next Bank of England MPC decision due on 30 April 2026.

The Bank of England base rate currently stands at 3.75%, held unchanged at the March 19 meeting. An April cut is possible but not certain. That uncertainty is flowing directly into mortgage pricing.

Best-buy products exist at lower headline rates but carry significant arrangement fees. Zephyr offers a two-year fix at 2.79%, but with a 7% arrangement fee attached. The Mortgage Works has a five-year fix at 4.29%. These headline rates are not directly comparable without factoring in the fee cost across the product term. (For the full analysis of that trade-off, see BTL Mortgage Fees in 2026.)

For context, the average five-year BTL rate in early 2021 sat around 2.6-3%. A landlord rolling off a 2021 five-year fix is looking at a rate roughly 2.5 to 3 percentage points higher on renewal.

The Stress Test in Practice: Worked Examples

The formula is:

Minimum monthly rent = (Loan balance × stress rate ÷ 12) × ICR threshold

Or, working with annual figures first:

Minimum annual rent = (Loan balance × stress rate) × ICR threshold

The following examples use a 5.5% stress rate and illustrative figures. They are educational, not financial advice, and do not represent any specific lender's criteria.

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Example A: £200,000 interest-only loan, basic-rate taxpayer (125% ICR)

• Annual interest at stress rate: £200,000 × 5.5% = £11,000
• Minimum rent required: £11,000 × 1.25 = £13,750 per year
• That is £1,146 per month

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Example B: £300,000 interest-only loan, basic-rate taxpayer (125% ICR)

• Annual interest at stress rate: £300,000 × 5.5% = £16,500
• Minimum rent required: £16,500 × 1.25 = £20,625 per year
• That is £1,719 per month

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Example C: £250,000 interest-only loan, higher-rate taxpayer in personal name (145% ICR)

• Annual interest at stress rate: £250,000 × 5.5% = £13,750
• Minimum rent required: £13,750 × 1.45 = £19,938 per year
• That is £1,661 per month

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Now compare these to what the same calculation produced in 2021 when some lenders were using a 5.0% stress rate. Example A at 5.0% and 125% ICR would have required £1,042/month. Today it requires £1,146/month. That is £104 more per month from a single floor rate change, nothing to do with the actual product rate.

Rents have risen since 2021, but in lower-demand areas, older tenancies, or properties where landlords have not been able to push rent to market levels, the gap can be enough to fail a test that passed comfortably before.

There is a compounding effect at higher loan-to-value. Some lenders apply a higher floor rate at 80% LTV or above, which can push the stress rate to 6% or more. Running Example A at 6% gives a minimum rent requirement of £1,250/month rather than £1,146.

For limited company BTL, some lenders allow top-slicing, where the director's other income can be factored in if the property alone does not pass the stress test in isolation. This is worth exploring if your property is borderline. For how the rules differ in a company structure, see Should I Incorporate My Buy-to-Let?.

What If You Fail the Stress Test?

Failing the stress test with one lender does not mean you cannot remortgage. It means that lender, or that product, will not work. Several routes are worth exploring.

Reduce your LTV by injecting capital. A lower loan balance reduces the stressed interest figure, which reduces the minimum rent requirement. If you have savings or equity elsewhere, reducing the loan can bring the numbers into range.

Switch lenders. Not all lenders apply the same floor rate or the same ICR threshold. Some specialist lenders use a 5.0% stress rate rather than 5.5%, or assess longer fixed terms against the actual product rate. A whole-of-market broker will know which lenders' criteria your property can pass before any application is made.

Top-slicing. Some lenders will factor in your personal income alongside the rental income when assessing affordability. This does not change the stress test formula, but it means a shortfall in rental coverage can be bridged by your other income. It is more commonly available through specialist and limited company lenders.

Specialist lenders. Lenders such as Paragon, Fleet Mortgages, Precise Mortgages, and Aldermore are built for the BTL market. Their rates are often higher than high-street products, but their criteria tend to be more flexible and their underwriters understand professional landlords.

Accept the SVR while you consider options. Standard Variable Rates are typically 7% or above. Sitting on SVR for six months on a £250,000 loan costs roughly £2,000 more in interest than a five-year fix at 5.5%. That is the real cost of waiting. Calculate it for your loan before deciding it makes sense.

If the numbers cannot be made to work at any accessible LTV or lender, selling may be worth considering. See our analysis of when to hold or sell a buy-to-let for a framework to work through that decision objectively.

When to Act

The remortgage process for a buy-to-let property takes longer than most landlords expect. Budget three to four months from starting conversations to completion. Most lenders allow you to secure a product up to six months before your current deal expires, so you can lock in a rate now and activate it when your fix ends.

Sitting on SVR while waiting for rates to improve has a real, calculable cost. Work it out for your specific loan. In most cases, even an average current rate compares favourably to SVR over a six to twelve month period.

Work with a mortgage broker who specialises in buy-to-let and has access to the whole market. For a simple single property at standard LTV with straightforward circumstances, some borrowers go direct successfully. For anything more complex, a specialist broker will save time and avoid failed applications.

Practical Checklist

Before you approach a lender or broker:

• Know your fix expiry date and how many months remain
• Know your outstanding loan balance
• Calculate your current LTV (outstanding balance divided by current property value)
• Work out your monthly rent against the ICR minimum for your loan size, stress rate, and tax status
• Check your EPC rating. Some lenders require a minimum of D or C and will not offer products below this threshold
• Have three to six months of bank statements showing rental income ready
• If you own four or more mortgaged buy-to-let properties, prepare a full portfolio schedule before approaching any lender

This article is for informational purposes only and does not constitute financial or investment advice. Tax rules and legislation change frequently. Always verify current rates with HMRC or GOV.UK and seek independent professional advice before making investment decisions.