Buy-to-let fixes can vanish overnight: London landlords with mortgages ending in 2027 should review them now

A buy-to-let deal you expected to refinance onto can disappear the same day if swap rates move against a lender.

That is the key point many landlords miss when they follow only Bank of England rate headlines. Fixed-rate mortgage pricing is driven heavily by swap rates — the market rates lenders use to price future funding — and those can move independently of the Bank Rate. When they rise sharply, lenders can withdraw or reprice fixed products with little warning.

There is no new law here and no new regulatory deadline. But there is a real refinancing risk for any landlord with a mortgage ending in the next 6 to 12 months. Leave it too late and the deal you budgeted for may be gone, the replacement rate may be materially higher, and the case may no longer fit your cashflow or the lender’s affordability test.

Why this matters more in London

In London, the stakes are higher because the loans are often bigger. A modest rate move on a large interest-only balance quickly turns into a meaningful monthly cost.

On a £400,000 interest-only mortgage, a rise from 4% to 6% increases annual interest from £16,000 to £24,000 — an extra £667 a month. On larger balances, the jump is more severe. That can erode margin on a single let and put pressure on affordability for a refinance.

It is not just the payment that matters. Lenders will also look at interest cover ratio (ICR) and stressed affordability, and those tests vary by lender and borrower profile. A landlord may therefore find that a higher refinance rate means borrowing less than expected, even if the property has been letting without issue.

Treat mortgage expiries as portfolio deadlines

For landlords with several properties, this is an administration problem before it becomes a finance problem. Mortgage end dates should be tracked with the same discipline as licensing renewals, gas safety records or lease events.

Your schedule should show, for each property:

• lender
• current rate
• fixed-rate end date
• loan balance
• early repayment charge end date
• reversion rate, if known
• portability
• latest estimated value
• current loan-to-value ratio

If several fixes end in the same quarter, that is not just diary management. It is concentration risk. A cluster of expiries during a volatile period can hit several properties at once.

Start earlier than many landlords do

The clearest action is to speak to a broker 6 to 12 months before a fixed rate ends, and sooner for complex cases. Waiting until the final 8 to 10 weeks leaves very little room if there are title issues, short leases, non-standard construction, mixed-use elements or weak EPC ratings that reduce lender choice.

In fast-moving markets, a few days can matter. Once a product is withdrawn, it is usually gone unless the application was already submitted and accepted under the lender’s rules.

Stress-test before the lender does

Landlords should model each property at a rate at least 1 to 2 percentage points above today’s available quote and check whether the asset still works.

Compare that figure against:

• actual rent
• likely void periods
• service charges and insurance
• repairs and maintenance
• tax reserves
• licensing or compliance works

If the refinance only stacks up at today’s best-case rate, the position is fragile. That is especially true for HMOs, highly leveraged single lets and personally held buy-to-lets where tax treatment already weighs on net returns.

Higher mortgage costs do not create a right to raise rent

If refinancing is likely to increase costs, plan tenant communication carefully. There is no automatic right to increase rent because the mortgage has become more expensive.

Any increase still has to follow the tenancy terms and the correct legal route — for example, a valid rent review clause or the Section 13 procedure for a periodic tenancy where applicable. Landlords should not build a refinance plan around a rent increase unless they are confident it is legally available and commercially realistic.

Keep an audit trail

If you manage property for clients, documentation matters. Keep dated records of:

• broker instructions
• lender updates
• product withdrawals or repricing
• revised illustrations
• offer deadlines
• client decisions

If a deal disappears before submission, record what changed and what the replacement cost was. That matters for complaint handling, internal review and basic professional risk management.

Three steps to take now

1. List every mortgage ending in the next 12 months and rank them by urgency, loan size and refinance difficulty.
2. Speak to a broker about any mortgage ending within 6 months — earlier if the property or ownership structure is complex.
3. Stress-test cashflow and hold a reserve of 2 to 3 months’ mortgage payments for any highly leveraged property.

Rentals & Sales can audit remortgage deadlines across your London portfolio and coordinate the broker, tenancy and compliance steps before a fixed rate expires.