Most 5-year fixed buy-to-let products are priced off the 5-year SONIA swap rate, not the Bank of England base rate. Here's where it stands, and what moves in it tend to mean for your refinancing.
Historical snapshot dated 7 October 2026. Figures are not a live market feed and should be independently checked before use.
| Date | 5yr SONIA swap |
|---|---|
| 24 Sep | 4.79% |
| 25 Sep | 4.76% |
| 28 Sep | 4.81% |
| 29 Sep | 4.80% |
| 30 Sep | 4.78% |
| 1 Oct | 4.73% |
| 2 Oct | 4.70% |
| 5 Oct | 4.74% |
| 6 Oct | 4.72% |
| 7 Oct | 4.76% |
52-week range: 3.52% – 4.81% — the current rate sits near the top of that range. Source: published SONIA swap market data. This chart is refreshed periodically; it is not a live feed and may lag the market intraday.
When a lender offers a 5-year fixed-rate buy-to-let product, it typically funds that commitment by locking in a matching 5-year swap rate — effectively the wholesale cost of fixing money for five years. The mortgage rate you're offered is broadly that swap rate plus the lender's margin, which covers their cost of capital, operational cost, risk appetite for the asset class, and profit.
That's why 5-year fixed BTL pricing can move within days of a swap rate shift, while the Bank of England base rate — which more directly drives variable and tracker pricing — can stay unchanged for months at a time. Swap rates move on the market's expectations of where rates are heading, not just where they are today.
When swap rates fall, lenders typically have room to cut fixed rates over the following one to a few weeks, though not every lender moves at the same pace or by the same amount. When swap rates rise — as they have done over the past year — fixed pricing tends to firm up on new business, though existing offers already issued are usually unaffected once accepted.
If you're approaching a remortgage, the practical question is usually timing: whether to lock in a rate now against the current swap curve, or wait on the expectation that rates may ease. That's a judgement call that depends on your own position, risk appetite and the specific deal — which is exactly the kind of thing worth a conversation before you commit.
This page is general market commentary, not personalised financial or investment advice. Rates, margins and criteria vary by lender and change frequently — speak to us for terms applicable to your own transaction.