General information, not financial advice. Every situation is different — for yours, consider a regulated adviser or a whole-of-market broker.

📌 The 60-second version

My household pays roughly £20,000 a year in interest — every penny of it on the mortgage — to a bank whose name starts with “HS” and ends with “BC” (I couldn’t possibly say which). That’s about £1,650 every month that vanishes before we’ve paid off a single pound of what we actually borrowed. It’s not a fee I chose; it’s the quiet cost of borrowing that most of us never sit down and total up. So I did. This is the real number and the specific, legitimate levers I’m using to bring it down over the next 12 months — no gimmicks, no dodging anything, just the admin banks quietly count on you to skip. I’ll publish what actually works, with the maths.

Why I’m writing this

I work in fintech — I read about money all day. And yet it still took a boring afternoon with a spreadsheet to see how much interest my own family hands over every year: about £20,000, and all of it on the mortgage. That’s around £1,650 a month going out purely as the cost of the loan, before a penny comes off the balance.

If that’s true for me — someone who does this for a living — it’s true for a lot of people who’ve never had reason to add it up. So I’m going to cut my own interest bill in the open, show the working, and turn what I learn into guides anyone can use.

🏠 Where it goes: it’s the mortgage

No credit-card interest, no big overdraft — for us it’s almost entirely one number: the mortgage. And that’s the useful part of the story, because for most households the mortgage is where interest lives — the balance is simply so much bigger than anything else. If you want the single biggest saving, it’s almost always hiding there.

The plan (and the rules I’ve set myself)

Two rules first, because they matter:

Rule	What it means
✅ Legitimate only	Switching, negotiating, refinancing, timing, overpaying — never anything that games a contract or dodges an obligation.
🧮 Show the maths	Every move gets a before/after number, so it’s real, not a vibe.

The main event: the mortgage

This is where my whole bill lives, so it’s where the real work is. The general levers people weigh here — and the ones I’m working through — are:

• Remortgaging in good time before a fixed term ends (letting it roll onto the lender’s standard variable rate is where a lot of money quietly leaks).
• Penalty-free overpayments within the annual allowance.
• Checking whether an offset arrangement makes sense given any savings.

I’m booking time with a whole-of-market broker rather than just accepting my current lender’s renewal offer. (Full guide: How to Pay Less Mortgage Interest in the UK.)

The other places interest hides (maybe not for me — possibly for you)

Mine happens to be all mortgage, but most people’s interest is a mix, so I’ll be covering these too as part of the series:

• 💳 Card interest — the most expensive money in any house; the usual lever is a 0% balance transfer with a real plan to clear it. (0% Balance Transfer Guide.)
• 🏦 Fees, overdrafts and FX — smaller, but the fastest to fix. (Avoiding UK Bank Fees, £0-Abroad Cards.)
• 💰 Idle savings — cash earning nothing while borrowing runs hot is a quiet loss too. (Best Ways to Earn Interest on Savings.)

What I’m not doing

No missed payments, no “one weird trick,” no shuffling money to dodge anything. The goal isn’t to beat the system — it’s to stop overpaying inside it. Most of this is money that’s available to anyone who does the admin banks are quietly counting on you to skip.

Follow the numbers

I’ll post a monthly update here with the real running total — what I tried, what it saved, what didn’t. If you’re carrying a big interest bill too, this series is for you.

FAQ

Is it really possible to cut your bank interest significantly?

Often yes — especially where a mortgage has rolled onto a standard variable rate. How much depends entirely on your rate, balance and timing, which is why any figures here are one household’s, not a promise.

What’s usually the biggest source of interest for a household?

For most people it’s the mortgage, simply because the balance is so large. That’s typically where the biggest single saving is — which is why it’s the first thing to look at.

Is this financial advice?

No. It’s one person’s account and general information about how these options work. For a decision about your own money, speak to a regulated adviser or a whole-of-market broker.