The Single Most Important Mortgage Decision You Will Make
Before you choose a lender, a term length, or even a property — you need to decide whether you want a fixed rate or variable rate mortgage. This decision determines how predictable your monthly payments will be, how exposed you are to interest rate movements, and how much flexibility you have to make changes over the coming years.
Neither type is universally better. The right choice depends on your financial situation, your risk tolerance, how long you plan to stay in the property, and your view on where interest rates are heading. This guide explains everything you need to know to make the right call for your circumstances.
What Is a Fixed Rate Mortgage?
A fixed rate mortgage locks your interest rate at a set level for an agreed period — typically two, five, or ten years. During this fixed period, your monthly repayment stays exactly the same regardless of what happens to the Bank of England base rate or general economic conditions. After the fixed period ends, your mortgage reverts to the lender's Standard Variable Rate (SVR) unless you remortgage to a new deal.
Fixed rate mortgages are the most popular choice in the UK by a significant margin. According to UK Finance data, over 80% of new mortgage lending is on fixed rate products, reflecting widespread demand for payment certainty during periods of interest rate uncertainty.
Advantages of Fixed Rate Mortgages
- Complete payment certainty. You know exactly what you will pay each month for the entire fixed period. This makes budgeting straightforward and eliminates the anxiety of watching interest rate news.
- Protection from rate rises. If the Bank of England raises the base rate during your fixed period, your payments are unaffected. This was particularly valuable during the rapid rate increases of 2022 and 2023.
- Easier financial planning. Fixed payments make it simpler to plan for other financial goals — saving for home improvements, school fees, retirement contributions — without worrying about mortgage payment fluctuations.
Disadvantages of Fixed Rate Mortgages
- You miss out when rates fall. If the base rate drops significantly during your fixed period, you are locked into your higher rate while variable rate borrowers benefit immediately.
- Early Repayment Charges (ERCs). Most fixed rate mortgages charge a penalty if you want to leave the deal before the fixed period ends — typically 1% to 5% of the outstanding balance. This can be thousands of pounds.
- Less overpayment flexibility. Most fixed rate mortgages cap annual overpayments at 10% of the outstanding balance. Exceeding this triggers ERCs.
- The fixed period ends. After two or five years, you face the "mortgage cliff" — reverting to the SVR, which is typically much higher than your fixed rate.
What Is a Variable Rate Mortgage?
Variable rate mortgages have an interest rate that can change over time. There are three main types:
Tracker Mortgages
A tracker mortgage follows the Bank of England base rate at a set margin above it. If the base rate is 4.75% and your tracker is "base rate plus 1%," you pay 5.75%. If the base rate rises to 5.25%, your rate automatically rises to 6.25%. Tracker mortgages are transparent and mathematically linked to a published rate — there is no discretion on the lender's part.
Discount Mortgages
A discount mortgage is set at a fixed percentage below the lender's SVR. If the SVR is 7% and you have a 2% discount, you pay 5%. However, unlike a tracker, the lender can change the SVR at their own discretion (within regulatory constraints). This introduces uncertainty — the lender is not directly tied to the base rate.
Standard Variable Rate (SVR)
The SVR is the lender's default rate that applies when your deal period (fixed or tracker) ends. SVRs are set by each lender individually and typically run 2 to 3 percentage points above the Bank of England base rate. No new borrower would voluntarily choose the SVR — it is a last resort. Always remortgage before reverting to SVR.
Fixed vs Variable: The Key Comparison
| Factor | Fixed Rate | Variable Rate |
|---|---|---|
| Payment certainty | Complete | None |
| Benefits when rates fall | No | Yes (tracker) |
| Protected when rates rise | Yes | No |
| Early Repayment Charges | Usually yes | Usually no |
| Overpayment flexibility | Usually capped at 10% | Often unlimited |
| Best initial rate | Depends on market | Often lower |
How the Bank of England Base Rate Affects Your Decision
The Bank of England base rate is the single most important external factor in the fixed vs variable decision. When rates are high and expected to fall, variable rate mortgages become relatively more attractive — you could benefit from rate cuts automatically without paying an ERC to remortgage. When rates are low and expected to rise, fixing is more appealing — you lock in the low rate before increases affect you.
The challenge is that nobody can reliably predict future interest rates — not economists, not banks, not government. The market's implied future rates (visible in swap rates) are the best available forecast, but they are regularly wrong. Decisions based on rate predictions are inherently uncertain.
A pragmatic approach: if variable rate payments would stretch your finances uncomfortably if rates rose by 2 percentage points, fix. If you have sufficient financial headroom to absorb rate increases and value flexibility, a tracker or short fix may serve you better.
What Length of Fixed Rate Term Should You Choose?
If you decide to fix, the next question is how long. The most common options are two-year and five-year fixes, with ten-year fixes available from some lenders.
Two-year fixes give you a shorter commitment and the opportunity to reassess sooner. They are a good choice if you expect rates to fall significantly within two years, or if you are likely to sell or substantially change your mortgage within that period. The downside is that you face more frequent remortgaging costs and more uncertainty about future rates.
Five-year fixes provide greater certainty and typically involve fewer remortgaging events over a long mortgage term. They suit people who value stability, plan to stay in their home for many years, and want to minimise the administrative burden of regular remortgaging. The rate is slightly higher than a two-year fix to compensate for the longer commitment.
Ten-year fixes offer maximum certainty but are the most restrictive. ERCs can apply for the entire decade, making it very costly to leave if your circumstances change significantly. Few borrowers choose ten-year fixes — they are most appropriate for those with very stable circumstances who are certain they will not need to change their mortgage for the full term.
The Remortgaging Treadmill: Planning Around Your Deal End Date
One of the most important — and most overlooked — aspects of the fixed vs variable decision is planning your exit. Fixed rate mortgages revert to the SVR when the deal ends, which could add hundreds of pounds to your monthly payment immediately. You should plan to remortgage before this happens.
Most lenders allow you to secure a new rate up to six months before your current deal expires. The moment your fixed period ends, you should ideally already have your next deal lined up. Allowing even one or two months on the SVR can cost a significant amount in unnecessary interest — particularly on larger loan amounts.
Which Should You Choose?
There is no single correct answer, but here is a practical framework:
- Choose a fixed rate if you need payment certainty, are near the limit of your affordability stress test, or are uncomfortable with the possibility of payments rising by hundreds of pounds per month.
- Choose a tracker if you have strong financial headroom, want the flexibility to make unlimited overpayments without ERCs, and are comfortable with payment variability.
- Choose a two-year fix if you expect rates to fall significantly soon, or anticipate major life changes (moving, changing income) within two to three years.
- Choose a five-year fix if you value certainty and are settled in your home for the medium term.
Always use our free Mortgage Calculator to model exactly how different rates and rate changes would affect your monthly payments and total interest cost before making your decision.
The Role of a Mortgage Broker
The mortgage market is complex. There are hundreds of products from dozens of lenders, and the best deal for your specific situation — income structure, deposit size, property type, credit profile — may not be the one advertised most prominently. A whole-of-market mortgage broker has access to deals not directly available to consumers and can compare the full market on your behalf. Many brokers charge no fee to borrowers, earning their income from lender commission instead.
Whether you ultimately choose fixed or variable, getting professional advice ensures you are comparing the full range of available options rather than just the products visible on comparison websites.
Conclusion
Fixed rate mortgages offer certainty and protection from rate rises at the cost of flexibility and potential savings when rates fall. Variable rate mortgages — particularly trackers — offer lower initial rates and greater flexibility but expose you to payment uncertainty. The right choice depends on your financial resilience, your plans for the property, and your personal comfort with uncertainty.
Use our Mortgage Calculator to compare what your monthly payments would look like under different rate scenarios, and model the total interest cost of fixed versus variable options over your expected holding period.