When taking out or remortgaging a mortgage in the UK, one of the most consequential decisions you will make is whether to fix your interest rate or track the Bank of England base rate. Get it right and you could save thousands. Get it wrong and you could find yourself paying over the odds — or facing a costly penalty to get out.
This guide explains clearly how each product works, what the risks and benefits of each genuinely are, what happens if you want to leave a deal early, and how to think about the decision for your own circumstances.
There is no universally correct answer. The right choice depends on your financial position, your appetite for uncertainty, and how long you plan to stay in your home — not on what rates are doing in the news.
A fixed-rate mortgage locks your interest rate — and therefore your monthly payment — at a set level for an agreed period. The most common fixed terms in the UK are two, three, five, and ten years, though some lenders offer shorter or longer options.
During the fixed period, your payment does not change regardless of what happens to the Bank of England base rate, inflation, or the wider mortgage market. If rates rise sharply, you are protected. If rates fall, you do not benefit — you continue paying the rate you agreed.
When the fixed term ends, your mortgage reverts to your lender’s Standard Variable Rate (SVR) — unless you remortgage or arrange a new deal. SVRs in 2025 typically sit between 6.5% and 8%, making it important to plan your next move before the fixed period expires.
Fixed rate in summary:
The rate and payment are certain for the full term. You are buying stability and predictability — and paying a small premium for it.
The rate and payment move with the base rate. You benefit directly when rates fall. You are exposed directly when rates rise. Transparency is the tracker’s defining feature — unlike other variable rate products, the lender has no discretion over the rate. It is determined entirely by the Bank of England.
A tracker mortgage has a variable interest rate that moves in direct relation to the Bank of England base rate (also called the Bank Rate). Your mortgage rate is set as a margin above the base rate — typically between 0.5% and 2% — and adjusts automatically whenever the Bank of England’s Monetary Policy Committee (MPC) changes the rate.
If the base rate is 4.5% and your tracker is set at base rate + 1%, your mortgage rate is 5.5%. If the base rate rises to 5%, your rate automatically becomes 6%. If the base rate falls to 4%, your rate becomes 5%. The change takes effect promptly — usually within days of the MPC’s announcement.
The MPC meets eight times per year to review the base rate. Rate decisions are announced publicly and in advance of the meeting schedule — so you always know when a potential change is coming, even if you do not know the outcome.
This is the most important risk to understand clearly before choosing a tracker.
When the Bank of England raises the base rate, your tracker rate rises by the same amount — immediately. There is no buffer, no delay, and no lender discretion. If the MPC raises rates by 0.5% at their next meeting, your monthly payment increases accordingly within days.
On a £250,000 repayment mortgage over 25 years at a tracker rate of 5.5% (base 4.5% + 1%), monthly payments are around £1,530.
If the base rate increases to 5.5%, payments rise to about £1,610 per month.
A further 2% increase in base rate can take payments to around £1,920 per month, significantly increasing total yearly cost.
Tracker mortgages can therefore become more expensive over time if interest rates rise during the term.
Those on a tight monthly budget where even a £100–£200 increase would create pressure should be cautious.
Self-employed, contractors, or variable-income borrowers may struggle if payments rise unpredictably.
Anyone close to their maximum affordability limit should avoid exposure to rate changes.
Households with limited savings buffer may find it difficult to manage sudden increases without cutting essential spending.
| Feature | Fixed Rate | BoE Tracker |
|---|---|---|
| Payment certainty | Yes — fixed for the term | No — changes with base rate |
| Protection from rate rises | Yes | No |
| Benefit from rate falls | No — locked in | Yes — immediate |
| Initial rate | Usually slightly higher | Often lower at outset |
| Transparency | Rate set by lender at outset | Rate = BoE base rate + fixed margin |
| Overpayment flexibility | Usually 10% per year ERC-free | Often more generous |
| Early exit cost | ERCs typically 1–5% | Often lower or no ERC |
| Suitable for | Budget certainty, rate rise concerns | Rate fall expectations, flexibility needs |
Using the same example of a tracker at base rate +1%, if the base rate falls from 4.5% to 4%, your rate reduces from 5.5% to 5%. On a £250,000 mortgage over 25 years, this could reduce payments by around £60–£70 per month. Any change in the base rate is automatically reflected, so your payments move up or down without action from you.
The main benefit of a tracker is transparency and immediate response to Bank of England rate changes. When rates fall, your monthly payments reduce straight away. However, if rates rise, your payments increase in the same way. Unlike fixed rates, there is no protection from increases, but you do benefit directly in a falling rate environment.
Some tracker mortgages include a collar, which sets a minimum rate your mortgage cannot fall below. For example, with a 2.5% collar and base rate drop, your rate will not go below the agreed floor. This means even if the base rate falls significantly, your payment may stay higher than expected. Always check if a collar applies before choosing a tracker deal.
A fixed rate protects you from rises — but it also locks you out of falls.
If you fix at 5% and the Bank of England cuts rates over the following two years, taking the base rate — and new tracker products — to a level that would give you a 3.5–4% tracker rate, you continue paying 5% until your fixed term ends. You are paying an above-market rate and cannot benefit from the change.
This is not a hypothetical risk. Borrowers who fixed at peak rates in 2022–2023 at 5–6% have faced exactly this situation as rates have gradually come down. Those on trackers during the same period have seen their payments fall as the Bank of England has cut rates.
The only way to exit a fixed rate early to benefit from lower rates is to pay an early repayment charge (ERC), and this cost can be substantial.
ERCs are almost always expressed as a percentage of the outstanding mortgage balance at the time of exit. The percentage typically reduces over the life of the deal.
Some tracker mortgages carry ERCs similar to fixed rates. Others carry no ERC at all — particularly lifetime trackers, which track the base rate for the full mortgage term and can typically be exited at any time without penalty. Always check the ERC terms of any tracker product before committing.
| Year of Exit | Year 1 | Year 2 | Year 3 | Year 4 | Year 5 |
|---|---|---|---|---|---|
| ERC | 5% | 4% | 3% | 2% | 1% |
| Year of Exit | Year 1 | Year 2 | Year 3 | Year 4 | Year 5 |
|---|---|---|---|---|---|
| ERC % | 5% | 4% | 3% | 2% | 1% |
| Approximate Cost | £12,500 | £10,000 | £7,500 | £5,000 | £2,500 |
| Year of Exit | ERC |
|---|---|
| Year 1 | 5% |
| Year 2 | 4% |
| Year 3 | 3% |
| Year 4 | 2% |
| Year 5 | 1% |
| Year of Exit | ERC % | Approximate Cost |
|---|---|---|
| Year 1 | 5% | £12,500 |
| Year 2 | 4% | £10,000 |
| Year 3 | 3% | £7,500 |
| Year 4 | 2% | £5,000 |
| Year 5 | 1% | £2,500 |
A lifetime tracker (sometimes called a term tracker) tracks the base rate for the entire remaining mortgage term rather than a set initial period. It offers a rate that moves with the base rate for life, with no deal end date and no reversion to SVR.
It is typically a no ERC product, meaning you can exit, remortgage, or make changes at any time without penalty. It is suitable for borrowers who expect rates to fall over the medium term or who value maximum flexibility. Although less common than two- or five-year products, it is still available from a range of lenders.
The absence of ERCs is its key advantage, allowing the holder to remortgage whenever it becomes beneficial, switch to a fixed rate if rates rise, or continue benefiting from rate reductions without restriction.
Once you have decided to fix, you face a further choice on term length. The most common options are two and five years. The broad principle.
Don’t rely on guesswork when choosing between fixed and tracker rates. We compare the full market and show you exactly how each option affects your monthly payments and long-term cost — based on your situation, not headlines.
Get clear, unbiased advice from Mortgage Knight and choose the mortgage that truly fits your needs.
A fixed rate mortgage locks your interest rate and monthly payment for a set period — typically two, three, five or ten years — regardless of what happens to the Bank of England base rate. A tracker mortgage has an interest rate set as a margin above the base rate, moving up or down automatically whenever the Bank of England changes it.
The Bank of England base rate (also called the Bank Rate) is the interest rate set by the Monetary Policy Committee, which meets eight times per year. It is the primary tool used to control inflation in the UK. When it rises, borrowing costs across the economy — including mortgages — generally increase. When it falls, they generally decrease. Tracker mortgages are directly linked to it; fixed rates are not affected during the fixed period.
Your mortgage rate rises by exactly the same amount, typically within days of the MPC announcement. Your monthly payment increases accordingly. On a £250,000 mortgage, a 1% base rate rise adds approximately £130–160 per month depending on your remaining term.
Nothing changes during your fixed term. You continue paying the rate you agreed regardless of market movements. To benefit from lower rates, you would need to wait until your fixed term ends — or pay an early repayment charge to exit early, which can cost thousands of pounds.
An ERC is a penalty for leaving a mortgage deal before its agreed end date. On fixed-rate mortgages, ERCs typically range from 1% to 5% of the outstanding balance, reducing each year of the deal. On a £250,000 mortgage in year one of a five-year fix, an ERC of 5% would cost £12,500. Some tracker mortgages carry no ERC at all.
