Buy-to-let rates are back at 5.9% — landlords with fixes ending by March 2027 should refinance now

Average buy-to-let fixed rates are back at roughly 5.9%, and that alone is enough to turn a routine refinance into a cashflow problem for landlords whose current deals end by 31 March 2027.

According to Mortgage Strategy, late-September 2026 lender repricing pushed the average two-year fixed rate to 5.92% and the average five-year fixed rate to 5.94%. Some fixed products increased by as much as 57 basis points, while some tracker and variable products rose by up to 47 basis points. There is no new legal rule here. The pressure is commercial: higher payments, tougher affordability and less room for delay.

Check the real end date first

One detail in the repricing matters more than it first appears. Mortgage Strategy reported that some lenders, including NatWest, Nottingham, RBS and Skipton, extended certain fixed-rate end dates by one month. That may help briefly, but it also creates an obvious administrative risk if your own records, your broker’s notes and the lender’s system do not match.

If a deal matures in the next six months, confirm the end date in writing with the lender or broker now. Do not rely on an old mortgage offer or an internal spreadsheet.

The payment jump is real

For landlords with larger debt balances, even a modest rise can materially change monthly cashflow. A 0.47% increase on a £400,000 interest-only loan adds about £157 a month in interest. On £750,000, it adds about £294 a month. A move from an older fixed rate below 4% to a replacement product near 6% is more painful again.

In London, where loan sizes are often larger and yields tighter, that extra cost can quickly absorb the margin that was covering repairs, service charges, letting fees and voids.

Headline rate is only part of the problem

The bigger refinance risk is not just price. It is whether the case still fits lender criteria once rates are near 6%.

Mortgage Strategy also pointed to ongoing changes in loan-to-value limits, interest-only availability, later-life borrowing and product availability. For portfolio landlords, that can reduce loan size or knock out an otherwise workable refinance. It matters especially in London, where older borrowers, larger mortgages and lower yields can make age-at-term and interest cover tests bite harder.

Stress-test deals ending by spring 2027

If your fixed rate ends between now and March 2027, run the numbers at 0.5% to 1% above today’s quote. That is not because another rate increase is confirmed; it is because lenders are repricing quickly and a product available this week may not be there next week.

This review should include the costs landlords often underweight: service charges, major works on leasehold blocks, insurance, compliance spend and likely void periods. On paper, a refinance may still pass. In practice, net cashflow may already be thin.

Rent increases are not a shortcut

Trying to recover higher finance costs through rent is not a compliance-free fix. For periodic tenancies in England, the usual route is a properly served Section 13 notice, unless the tenancy agreement provides another valid mechanism. During a fixed term, you would usually need a valid rent review clause or the tenant’s agreement.

There is no London-wide rent control regime currently in force in England. But landlords should not confuse market pressure with legal entitlement: an invalid notice, an unaffordable jump or a resulting void can leave the numbers worse, not better.

Agents should treat this as a portfolio-risk issue

For letting agents and portfolio managers, this is also a client communication issue. Landlords with refinancing dates inside the next six months should be told, in clear terms, their likely refinance window, the probable payment change and the latest sensible point to speak to a broker.

That is not about giving regulated mortgage advice. It is about reducing the risk of arrears, rushed decisions and disputes later.

What to do now

Within 7 days: compile a full mortgage schedule and verify every product end date directly with the lender or broker.

Within 14 days: rework affordability and cashflow at today’s pricing and at 1% higher, especially on larger London loans and leasehold flats with high service charges.

Before any rent increase: check the tenancy type, the correct notice route and whether the increase is commercially realistic as well as legally valid.

This article is general information, not mortgage, legal or tax advice.

R&S can help by reviewing your tenancy position, notice route and portfolio paperwork before a refinance-linked rent increase or management change creates a more expensive problem.