Fixed-rate mortgage: what it is and how it works

A fixed-rate mortgage is designed to give you greater certainty. Instead of your interest rate changing month to month, the rate is fixed for an agreed period—so your mortgage payments are intended to remain stable during the fixed term (subject to the mortgage being set up in the usual way and assuming no other changes).

This guide explains what fixed-rate mortgages are, the main trade-offs to consider, the costs to look out for, and what typically happens when the fixed period ends.

What is a fixed-rate mortgage?

A fixed-rate mortgage is a repayment or interest-only mortgage where the interest rate is fixed for a set term.

Common fixed terms include:

• 2-year fixed
• 3-year fixed
• 5-year fixed
• 10-year fixed

During the fixed period, the lender sets the interest rate for that term. That means you’re generally not exposed to day-to-day movements in interest rates while the fix is in place.

Note: while your interest rate is fixed, the way your mortgage balance reduces over time will still depend on whether it’s a repayment or interest-only mortgage.

Fixed vs variable rate mortgages

Variable rate mortgages

With a variable rate mortgage, the interest rate can change during the mortgage term. Some variable products move in line with a reference rate; others can change based on the lender’s pricing.

Fixed rate mortgages

With a fixed rate mortgage, the interest rate is intended to stay the same for the fixed term. Many borrowers choose fixed deals when they want predictability, particularly if they’re budgeting tightly or want to reduce uncertainty about what could happen to repayments.

How long can you fix for?

Fixed terms vary by lender and product availability, but for home buyers the most common options are often 2-year and 5-year fixes.

In general:

• Shorter fixes can offer more chances to review your options sooner.
• Longer fixes can provide stability for longer, but may involve stronger commitment and potentially higher costs if you need to leave early.

Choosing between a 2-year and 5-year fixed

There isn’t a single “best” fixed term length. The right choice usually depends on your plans and how much flexibility you want.

2-year fixed: often chosen for flexibility

A 2-year fix may suit you if you:

• want the opportunity to review your mortgage sooner
• think you may move, remortgage, or restructure within the next few years
• prefer to keep more options open

5-year fixed: often chosen for longer stability

A 5-year fix may suit you if you:

• want stability for a longer period
• prefer not to worry about rate changes during the fixed term
• expect to stay in the property for most of the fixed period

A practical consideration is that the longer the fixed term, the more important it becomes to understand the costs of leaving early.

What happens when the fixed term ends?

When your fixed period ends, your mortgage will normally move onto a new interest rate arrangement.

Common outcomes include:

• moving onto a new deal (often by remortgaging or switching products)
• moving onto the lender’s standard variable rate (SVR) or another variable rate set by the lender

The key point is that your repayments may change at the end of the fixed period, depending on the rate you move onto.

Pros of a fixed-rate mortgage

Fixed-rate mortgages can be appealing when you value certainty.

Payment certainty during the fixed term

A fixed rate can make it easier to plan household spending because your interest rate is intended to remain unchanged for the duration of the fix.

Protection from rate rises while fixed

If interest rates rise after you take out your mortgage, your rate is intended to remain the same throughout the fixed period.

Useful for matching your timescale

A fixed deal can align with a realistic plan for how long you expect to keep the mortgage.

Cons and trade-offs to consider

Fixed-rate mortgages are not automatically the best choice for everyone. The main trade-offs usually relate to flexibility and the cost of leaving early.

Early repayment charges (ERCs)

Many fixed-rate mortgages include early repayment charges if you repay the mortgage during the fixed period.

The exact structure varies by lender and product, so it’s important to understand the ERC terms for the specific deal you’re considering.

If rates fall, you may not benefit immediately

If interest rates drop after you take out your fixed deal, you generally can’t simply switch to a lower rate without considering the impact of ERCs and the product’s switching rules.

Your plans may change

Life events—such as moving sooner than expected, changes in income, or other financial changes—can affect whether you keep the mortgage for the full fixed term.

Key costs to look for on fixed-rate deals

When comparing fixed-rate mortgages, it’s helpful to look beyond the headline interest rate.

Upfront fees

Many fixed-rate mortgages have an arrangement, product or completion fee. These can affect the overall cost of the mortgage, especially if you don’t plan to stay for the full term.

Early repayment charges (ERCs)

ERCs apply if you repay the mortgage early (in full or sometimes in part, depending on the deal).

Overpayment rules

Some fixed-rate mortgages allow overpayments, but the rules can vary significantly. You may see features such as:

• an annual overpayment allowance
• overpayments that may be free of charges up to a limit
• overpayments beyond the allowance that may be subject to charges

If overpaying is part of your plan, the overpayment terms can matter as much as the interest rate.

Fixed-rate mortgages and moving home

If there’s a possibility you’ll move during the fixed period, it’s important to understand how the mortgage can be handled.

Two broad approaches are commonly discussed:

• porting the mortgage to a new property (where allowed by the lender and subject to conditions)
• repaying and taking a new mortgage on the new property (which may trigger ERCs, depending on the product)

Whether porting is available and how ERCs apply depends on the mortgage terms and lender rules.

Fixed-rate mortgages for first-time buyers

For first-time buyers, a fixed rate can be attractive because it can help with budgeting certainty during the early stages of homeownership.

It may be particularly relevant if you:

• want to reduce uncertainty about future repayments
• are working to a defined affordability figure
• expect to stay in the property for much of the fixed term

The trade-offs still apply—especially around flexibility and the potential cost of leaving early.

Fixed-rate mortgages for remortgage borrowers

For remortgage borrowers, a fixed rate can be a way to manage the transition when an existing deal ends.

It may be relevant if you:

• want to avoid moving onto a lender’s SVR
• want repayment stability for the next stage of your mortgage

As with any fixed deal, it’s important to review ERCs, overpayment rules, and what options you’ll have at the end of the new fixed period.

Is a fixed-rate mortgage right for you?

A fixed-rate mortgage may suit you if you:

• want repayment certainty for a defined period
• are comfortable with the idea of being tied in during the fixed term
• have a realistic plan to stay in the property long enough for the fix to be worthwhile

It may be less suitable if you:

• expect you might need to move or refinance early
• have uncertain plans and want maximum flexibility
• want the ability to respond quickly if interest rates change

A sensible approach is to match the fixed term length to your timescale and understand the potential cost of leaving early.

Summary

A fixed-rate mortgage provides stability by keeping your interest rate the same for an agreed period. The main considerations are the balance between certainty and flexibility, particularly around early repayment charges, overpayment rules, and what happens when the fixed term ends.

Choosing between common fixed terms such as 2, 3, 5 or 10 years typically comes down to how confident you are about your future plans and how you weigh the trade-offs.