When SONIA swap rates (Sterling Overnight Index Average - the cost at which banks fund mortgages) jumped sharply last week, something familiar happened: lenders started pulling products and repricing existing deals. It felt like a financial convulsion. For property investors and remortgagors, it was. The question everyone asks is whether this is 2022 all over again - the Truss mini-Budget chaos redux. The answer is more nuanced, but no less serious for your wallet.

How lenders price your mortgage rate

Here's the mechanism that matters. Lenders don't price fixed-rate mortgages off today's Bank Rate. They price them off what they expect to pay for their own funding over the next five or ten years. That expectation lives in the swap rate market. When traders suddenly repriced expectations upward - pushing two-year SONIA swaps to 4.483%, three-year to 4.420%, and five-year to 4.346% (Mortgage Finance Gazette, 23 March 2026) - lenders' funding costs rose immediately. Within 48 hours, those costs flowed into your mortgage quote.

Nicholas Mendes of John Charcol captured it simply: "Lenders price fixed rates off future funding costs, not simply where Bank Rate sits today" (Mortgage Finance Gazette, 23 March 2026). That distinction is everything. You could have a 5% Bank Rate environment with falling swap rates (cheaper mortgages), or a 4% Bank Rate with rising swap rates (more expensive mortgages). The Bank Rate is noise. The swap rate is signal.

What changed this time

The parallel to 2022 is real but incomplete. In September 2022, the Truss mini-Budget sparked a broader crisis of confidence in UK fiscal credibility. Yields spiked across the board. Mortgage rates, credit spreads, and gilt yields all moved together in a panic. This week's repricing is narrower: it's about rate expectations, not systemic fiscal credibility.

"A sharp shift in rate expectations, higher swap pricing, and concern that policy may need to stay tighter for longer" are driving the repricing (Mortgage Finance Gazette, 23 March 2026). The Bank of England may hold Base Rate steady. That isn't the point. What matters is whether inflation stays sticky and whether rate expectations shift further up. If traders believe the bank needs to keep rates higher for longer than previously assumed, swap rates move up. Your mortgage gets more expensive, regardless of what the Bank Rate does next week.

Lenders responded predictably. Coventry for Intermediaries pulled all new customer deals entirely. Aldermore, Metro, TSB, and others either withdrew specific products or repriced upward (Mortgage Finance Gazette, 23 March 2026). When multiple lenders exit a cohort simultaneously, it signals they've recalculated their funding costs and don't like the new math.

Tax implications for remortgaging investors

This repricing arrives at a moment when tax considerations make timing even more acute. If you're a Buy-to-Let (BTL) landlord remortgaging, higher swap rates compound the financial pressure. Under Section 24 of the Finance (No. 2) Act 2015 (fully phased in by April 2020), you already cannot claim mortgage interest as a deduction against rental income - you get only a basic rate tax credit instead. When swap rates spike and your mortgage costs rise, that bill doesn't shrink your taxable profit. Instead, the increased interest portion of your payments comes from post-tax cash. Timing your remortgage offer now, before costs rise further, directly affects how much post-tax income you'll need to service the debt for the next five years.

For investors facing capital gains tax (CGT) on a future sale, higher borrowing costs now also influence the net proceeds calculation. A £625 annual increase (Mortgage Finance Gazette, 23 March 2026) multiplied across a five-year hold reduces your profit margin. When it's time to dispose, that narrower margin may push you closer to CGT liability on a second property or influence your decision to keep or sell. Securing an offer three to six months ahead locks pricing and gives your accountant certainty for tax planning.

What to do before your remortgage

For investors approaching a remortgage, waiting for rate cuts is a gamble the numbers no longer support. If your fix ends in six to twelve months, you should "speak to a broker early" rather than assuming prices will fall closer to the deadline (Mortgage Finance Gazette, 23 March 2026). Better still, if you're within the window, securing a new mortgage offer three to six months ahead is worth serious consideration. You lock in today's pricing rather than gambling on tomorrow's. That costs nothing (subject to lender terms), and it removes uncertainty from your cash flow forecast.

For a worked example: assume a £250,000 fixed-rate mortgage, five-year term. A 25 basis-point rise in swap rates (0.25%) translates to roughly £625 extra per year in your interest bill - assuming the lender passes the full cost through, which it typically does. Over five years, that's £3,125. Multiply that across a portfolio of remortgages, and you see why this week mattered.

The deeper risk is that swap rates don't move in isolation. If funding costs stay elevated, lenders tighten lending criteria (higher deposit requirements, stricter affordability tests). That happened in 2022. It's happening again, more quietly. Your mortgage may be pricier and harder to obtain if conditions tighten further.