Buy-to-Let Rates: Why the Late-Summer Cuts Have Already Been Overtaken

If you looked at buy-to-let mortgage rates through August, you'd have seen a run of cuts. NatWest trimmed selected buy-to-let fixed rates by up to 0.22 percentage points, Landbay cut pricing across its Premier, Core and Specialist ranges by up to 0.35 points, and BM Solutions and Coventry for Intermediaries reduced rates too. Santander followed from 19 August, cutting its buy-to-let range by up to 0.13 points. It looked, briefly, like the start of a cheaper autumn.

It wasn't. The funding cost underneath those cuts has moved sharply against borrowers since, and the mortgage market is only now starting to catch up.

The Late-August Cuts Were Real, But They Were Already Behind the Curve

Fixed-rate buy-to-let mortgages aren't priced off Bank Rate. They're priced off swap rates and gilt yields, the cost of the money a lender borrows over two, three or five years to fund your fixed deal. Bank Rate has sat at 3.75% since the Bank of England's fifth consecutive hold on 30 July, and it stayed there through the whole of this episode. Swaps and gilts did the moving.

Through most of August, that funding backdrop was genuinely easing, which is why the cuts happened. But swap rates and gilt yields both turned sharply higher in the first days of September, driven in large part by a jump in oil prices after a flare-up in the Gulf and a bond market that's been jumpy about government borrowing right across the developed world, not just in the UK. The lenders cutting rates in late August were pricing off a market that no longer exists.

Frequently Asked Questions

Are buy-to-let mortgage rates going up or down in September 2026?

Up, after a period of cuts through late August. The swap rates and gilt yields that fund fixed-rate buy-to-let deals have risen sharply since the start of September, and best-buy tables have started reflecting that within the last fortnight. The late-August cuts were real, but they were priced off a funding market that has since moved against borrowers.

Why do buy-to-let mortgage rates move when the Bank of England hasn't changed Bank Rate?

Most buy-to-let deals are fixed for two, three or five years, and lenders fund them by borrowing at matching swap rates, which track gilt yields rather than Bank Rate. Bank Rate has sat at 3.75% since July 2026. Five-year swaps have moved from around 4.16% to above 4.5% in the same window, and that is what is actually driving your next quote.

What is the average buy-to-let mortgage rate right now?

Moneyfacts put the overall average fixed buy-to-let rate at 5.47% on 1 August 2026, the last confirmed whole-market reading. Its two-year and five-year splits have kept climbing since, reaching 5.32% and 5.70% at the start of September. These are two different measures and shouldn't be quoted interchangeably.

Should I fix my buy-to-let mortgage now given rates are rising?

There's no single right answer, and this isn't financial advice. What's worth knowing is that best-buy tables typically lag the underlying funding market by two to four weeks, so a rate you see advertised today may already be stale by the time you apply. Speaking to a whole-of-market broker who can check live pricing, and re-running your numbers at a range of rates rather than one fixed assumption, are both more useful than trying to time the exact bottom.