TL;DR: A tracker mortgage is a UK mortgage product where the interest rate is set as a fixed margin above (or rarely below) the Bank of England base rate, and moves up or down whenever the base rate changes. If the Bank of England base rate is 4.5 percent and the tracker margin is 0.75 percent, the mortgage rate is 5.25 percent; when the Bank base rate moves to 4.25 percent, the mortgage rate becomes 5.00 percent automatically. Tracker mortgages are typically offered for 2-5 year initial periods, after which the mortgage reverts to the lender's standard variable rate or moves to a new deal. The main advantage is that the borrower benefits immediately from rate cuts; the main disadvantage is that the borrower is exposed to rate rises with no cap (unless the product has a specific cap or "collar" clause). Trackers are often combined with no early repayment charge, giving flexibility to switch.
Last reviewed May 2026
UK mortgages come in three main rate structures: fixed (the rate is set for the deal period and does not change), discounted variable (the rate is the lender's standard variable rate minus a margin, and changes when the lender's SVR changes), and tracker (the rate is a fixed margin above an external reference rate, typically the Bank of England base rate, and changes when the reference rate changes). Tracker mortgages have grown in market share when borrowers expect rates to fall.
This guide explains the mechanics of a tracker mortgage, the difference between tracking the Bank of England base rate and tracking other indices, the term and reversion structure, the role of early repayment charges (or their absence), the comparison between trackers and fixed-rate products at different points in the rate cycle, and the FCA framework that protects borrowers.
How a tracker mortgage rate is set
A tracker mortgage rate consists of two parts: the reference rate (typically the Bank of England base rate, set by the Monetary Policy Committee) and a fixed margin (the lender's premium above the reference rate). The borrower's interest rate is the sum of the two. When the reference rate moves, the borrower's rate moves by the same amount, usually within days of the Bank of England announcement.
The margin (sometimes called the "tracker differential") is set when the mortgage is taken out and does not change during the tracker period. A borrower on Bank base rate plus 0.75 percent has a rate of 5.25 percent when the base rate is 4.5 percent, 5.00 percent when it falls to 4.25, and 5.50 percent if it rises to 4.75. The margin reflects the lender's funding cost margin, profit margin and credit-risk view of the loan.
The Bank of England publishes the base rate decision on the day of the Monetary Policy Committee meeting (every six weeks, generally). Lenders typically pass through any change to tracker mortgage rates from the start of the next month, though the exact timing varies and is specified in the mortgage offer.
The tracker period and reversion
Tracker mortgages typically have an initial tracker period of 2, 3 or 5 years. During this period, the rate is the Bank base rate plus the agreed margin. After the tracker period ends, the mortgage normally reverts to the lender's standard variable rate (SVR), which is set by the lender and may be significantly different from a base-rate tracker.
The SVR is typically 2-3 percentage points above the Bank base rate, so the reversion can be a material rate increase. Most borrowers either remortgage to a new product before the tracker period ends or take a product transfer with the same lender. Lenders accept remortgage applications up to 6 months before the deal end date, which is normally enough time to line up the new product.
Some lifetime tracker mortgages (rarer in the modern market) track the Bank base rate for the full mortgage term, with no reversion to SVR. These products have largely disappeared from new lending but some legacy mortgages from before the financial crisis are still on lifetime trackers and remain advantageous to the borrower as long as the base rate stays well below historical norms.
Early repayment charges (or their absence)
One of the historical advantages of tracker mortgages is that many products have no early repayment charge (ERC). This gives the borrower the flexibility to switch to a fixed rate, redeem the loan from a property sale, or remortgage to a new lender at any time without penalty. The flexibility is particularly valuable when rate direction is uncertain.
Not all trackers are ERC-free. Some have a stepped ERC (typically 2 percent in year 1, 1 percent in year 2, then zero), which is shorter and lower than the typical fixed-rate ERC. The mortgage offer specifies the exact terms.
The combination of base-rate tracking and no ERC makes some trackers very flexible products: the borrower benefits from rate cuts immediately and can switch out if rates rise materially without penalty. This is the appeal for borrowers who are uncertain whether to fix or wait.
Tracker versus fixed rate: the trade-off
A fixed-rate mortgage gives certainty about the monthly payment for the deal period, at the cost of not benefiting from any rate cuts. A tracker gives immediate participation in rate moves (up and down), at the cost of payment uncertainty. The decision depends on the borrower's view on rate direction and their tolerance for payment variability.
When the market expects rates to fall, trackers look attractive because the borrower captures the cuts immediately. When the market expects rates to rise, fixed-rate products look attractive because they lock in the current rate. The market-implied path is partly visible in the swap rate curve and in the relative pricing of trackers and fixed-rate products at the same lender.
Many borrowers find a middle path: a 2-year tracker (with no ERC) followed by a remortgage to a fixed rate. This gives some flexibility while not betting the whole deal period on the rate path. The total cost over 2 years (tracker rate movements plus arrangement fees) versus a 2-year fix at the alternative rate is the right comparison.
Caps, collars and capped trackers
Some tracker mortgages include a cap (a maximum rate the borrower will pay regardless of the base rate moving higher) and / or a collar (a minimum rate the borrower will pay regardless of the base rate moving lower). A capped tracker limits the upside risk for the borrower; a collar limits the downside benefit.
Capped trackers were more common in the 2000s than they are today. The cost of the cap is built into a higher margin or a higher product fee. In a market where rates are stable or falling, capped trackers offer little advantage over a regular tracker, which is one reason they have become rare.
Some legacy trackers from the pre-2008 era include collars that prevent the rate falling below a stated floor, which became economically significant after the Bank base rate was cut to historic lows in 2009. The Financial Conduct Authority required lenders to disclose collars more prominently after complaints; existing collared trackers are honoured per the original mortgage terms.
The Bank of England base rate as the reference
The Bank of England base rate is the most common reference for UK tracker mortgages. It is set by the Monetary Policy Committee in pursuit of the Bank's inflation target. The rate has ranged from 0.10 percent (March 2020) to 5.25 percent (August 2023-July 2024), with adjustments throughout 2024-25 as inflation moderated.
A small number of trackers use other references: 3-month SONIA (the Sterling Overnight Index Average, which replaced LIBOR for most sterling references in 2022), a specific lender's cost of funds, or the prevailing gilt yield. Each has slightly different volatility and reset characteristics. Most mainstream borrowers will see a Bank of England base rate tracker.
The reference rate's stability matters for the borrower. The Bank of England base rate changes only at scheduled Monetary Policy Committee meetings (every six weeks), giving predictability about when adjustments happen. References that change more frequently (such as the daily SONIA) can produce more volatile borrower rates if the lender resets often.
Application criteria and stress testing
Tracker mortgages are subject to the same FCA affordability rules as other regulated mortgages. The lender stress-tests the borrower's affordability at a rate higher than the initial tracker rate, to assess resilience if rates rise. The stress test rate is set by the lender, typically 1-3 percent above the higher of the initial rate and the lender's SVR.
The stress test is particularly important for trackers because the borrower has direct rate exposure during the deal period. A borrower who can just barely afford the initial tracker rate may be unable to afford payments if the base rate rises significantly. The lender's stress test is the regulator-mandated check on this risk.
Loan-to-value (LTV) requirements for trackers are similar to fixed-rate products. The best tracker rates are usually at lower LTVs (60-75 percent), with higher LTV bands attracting larger margins. The product fee structure also follows the standard market pattern.
How we verified this
This article reflects the FCA's Mortgage Conduct of Business Sourcebook (MCOB) rules on tracker mortgage disclosure, stress testing and advice, the Bank of England's published methodology for setting the base rate, the Sterling Overnight Index Average documentation following the LIBOR transition, and UK Finance's published market data on UK mortgage product mix. Specific lender rates, margins and ERC structures are published in each mortgage offer and on each lender's website.
Disclaimer: This article is general information about UK tracker mortgages and is not personal financial advice. The choice between a tracker and a fixed-rate mortgage depends on the borrower's circumstances, view on rate direction, and tolerance for payment variability. A whole-of-market mortgage broker authorised by the FCA can model the trade-off for a specific case and identify the lenders offering the most cost-effective trackers.
Frequently asked questions
What is a tracker mortgage?
A tracker mortgage is a UK mortgage where the interest rate is the Bank of England base rate plus a fixed margin set when the mortgage is taken out. When the Bank of England changes the base rate, the borrower's rate changes by the same amount within days. Tracker mortgages typically have initial deal periods of 2, 3 or 5 years, after which the mortgage reverts to the lender's standard variable rate.
What is the difference between a tracker and a fixed-rate mortgage?
A fixed-rate mortgage has a rate that does not change during the deal period; a tracker mortgage's rate moves with the Bank of England base rate. The fixed product offers payment certainty; the tracker offers immediate participation in rate moves (up and down). The right choice depends on the borrower's view on rate direction and tolerance for payment variability.
Can my tracker mortgage rate go up?
Yes. When the Bank of England base rate rises, the tracker mortgage rate rises by the same amount, usually within days. There is no cap on how high the rate can go unless the specific product has a capped tracker structure (which is rare in the modern UK market). The lender's stress test at application is designed to verify the borrower can afford payments if rates rise.
Are tracker mortgages cheaper than fixed-rate mortgages?
It depends on the rate path during the deal period. Trackers typically have lower initial rates than fixed-rate products of the same term when the market expects rates to fall, and higher initial rates when the market expects rates to rise. The total cost over the deal period depends on what the Bank of England actually does, not just the initial rate.
Can I switch from a tracker to a fixed rate during the deal period?
Some tracker mortgages have no early repayment charge, making the switch free of penalty. Others have a stepped ERC. The borrower's specific offer is the definitive answer. A product transfer to a fixed rate with the same lender is usually the simplest route; a remortgage to a new lender is also possible if the ERC (if any) is acceptable.
