Buy-to-let mortgage rates are rising again as volatility in swap rates forces lenders to pull and reprice fixed-rate products upward, creating an unexpected refinancing bottleneck for thousands of landlords.

While attention remains focused on Bank of England base rate decisions, fixed-rate buy-to-let mortgage pricing is driven largely by swap rates – the cost to lenders of hedging interest-rate risk over two- to five-year terms. A sudden upward drift in short-term swap rates has prompted major lenders, including HSBC, NatWest, and Barclays, to increase fixed rates by 25 to 40 basis points, as highlighted in recent Moneyfacts market tracking.

More than 180,000 landlords face refinancing hit

The timing presents a significant challenge for property investors. According to UK Finance mortgage market data, 1.8 million fixed-rate mortgages are due for renewal this year, with BTL lenders such as Paragon Bank noting significant maturity volumes. Many of these landlords are coming off five-year fixed deals secured in 2021, when average rates sat between 1.8% and 2.4%.

With current two- and five-year fixed buy-to-let rates settling between 4.8% and 5.5% - and Interest Coverage Ratio (ICR) stress tests remaining strict at 125% to 145%, the financial gap at point of refinance is substantial.

For example:

• A landlord refinancing an average £200,000 interest-only buy-to-let mortgage moving from a 2.1% fixed rate to a 5.2% fixed rate will see annual interest payments jump from £4,200 to £10,400

• This adds £516 per month in debt-servicing costs alone, before accounting for management fees, maintenance, or tax obligations

Why compounding pressures leave little room for error

The rate increase coincides with broader operational cost pressures across the private rented sector. Landlords are already managing higher administrative expenses around regulatory compliance, energy efficiency planning, and extended court timelines for possession claims.

With new legislative rules capping rent increases strictly to once a year via formal notice, landlords have reduced scope to make incremental rent adjustments to offset sudden borrowing hikes.

Three practical steps for refinancing landlords

Brokers suggest landlords due to refinance in the next six to 12 months take early action:

1. Lock in product transfers early: Most lenders allow borrowers to secure a new rate up to six months before their current term expires without penalty

2. Review portfolio leverage: Capital top-ups or partial deleveraging may be required on lower-yielding properties to meet strict lender ICR calculations

3. Explore specialist lending options: Specialist brokers may be able to find lenders that use a landlord’s personal income to support a mortgage application when rental income falls short of the lender’s affordability requirements – a process known as ‘top-slicing’.

Ultimately, while the private rented sector has proven resilient through tax changes and regulatory shifts, maintaining a viable buy-to-let portfolio will increasingly depend far less on passive capital growth and much more on active, forward-looking debt management.