The cost of borrowing has jumped sharply. Two-year fixed mortgage rates hit 5.75% on 27 March 2026, according to Moneyfacts data published by Mortgage Finance Gazette. That is up 92 basis points (bps - each worth 0.01%) since the outbreak of war in Iran on 26 February. For SA operators - those running short-term let (STL) portfolios under schemes like Airbnb - the timing is difficult. Financing costs have risen fast.

On 26 February, before the military escalation, the average two-year fix sat at 4.83% (Moneyfacts). Average five-year fixed rates also rose, reaching 5.69% on 27 March, up 74 basis points from 4.95% (Moneyfacts, cited by Mortgage Finance Gazette, 27 March 2026). Overall average mortgage rates have now hit their highest level in 19 months.

How the Rate Spike Affects Your SA Cash Flow

SA (serviced accommodation) portfolios typically run on buy-to-let (BTL) mortgages or commercial finance. When rates spike by nearly a full percentage point, your monthly repayment increases directly. On a £250,000 mortgage over 25 years, a 92-basis-point increase adds roughly £135-£145 per month to a capital repayment deal. This is based on standard repayment calculations applied to the Moneyfacts rate data.

Your nightly rates need to cover occupancy, cleaning, council tax, utilities, and now a higher mortgage payment. If guest demand softens - which geopolitical uncertainty tends to cause - you cannot always pass the full cost increase on through higher nightly pricing without hitting your occupancy rates. Void periods become more expensive when the financing floor has moved up.

The impact multiplies across a portfolio. Two or three SA properties refinancing at the new rates rather than pre-war levels changes your annual cash flow materially. That's before accounting for the fact that lender criteria for SA and short-term let mortgages tend to be tighter than standard BTL.

What's Happened to Product Availability

Lenders have pulled and repriced deals in response to market uncertainty. Mortgage Finance Gazette reported on 27 March 2026 that roughly 160 products returned to the market during that week, but overall product availability remains well below pre-conflict levels. Fewer choices at higher prices is the operating environment right now.

If your mortgage fix expires in the next six to twelve months, you are now choosing from a compressed market. Lenders widen their margins during periods of elevated volatility and default concern. Swap rates (the benchmark interest rates that mortgage lenders use to price fixed deals) have moved sharply. The 92-basis-point jump also reflects lender appetite shifting under uncertainty.

SA-specific products and holiday let mortgages are a specialist segment. They move with the broader market but tend to have fewer options than standard BTL. The tighter the market, the fewer deals available to SA operators at competitive rates.

What SA Operators Should Consider Now

You may wish to speak to your broker about your refinancing timeline. If you have 12 to 18 months before a fix expires, consider modelling scenario rates at 6% and 6.25% to stress-test your cash flow. That's not a prediction - it's prudent planning. Geopolitical uncertainty tends to persist, and swap rates won't necessarily fall quickly.

Consider reviewing your SA properties for occupancy stress at higher financing costs. If your nightly rate revenue doesn't cover the new cost base, your property moves from cash-generative to cash-negative. Properties that worked on pre-war rate assumptions may need reassessment.

You may also wish to speak to your accountant about the tax treatment of higher interest costs. BTL and commercial mortgage interest is deductible against SA rental income. A higher interest bill means a larger tax-deductible expense - small comfort, but it's part of the total picture.

As for new SA acquisitions: consider pausing until rate volatility eases. The purchase maths that worked three weeks ago may not stack now. Running yield calculations at 5.75% rather than 4.83% changes whether a property makes sense to buy.