The ultimate guide to mortgage rates

Many people assume the Bank of England (BoE) directly sets your mortgage interest rate, but it does not.

The BoE held the base rate again at 3.75% in September, despite the EU and US raising theirs in the same month, meanwhile mortgages rates are at their highest level for nearly 3 years.

So how is the interest rate on your mortgage set, and who by?

The BoE Monetary Policy Committee (MPC) meets eight times a year to set the “Bank Rate”. That is the official name for the interest rate the Bank of England – our central bank, owned by the state – pays financial institutions that deposit money with it overnight.

More commonly known as the “base rate”, it is the core UK interest rate, but there is an important distinction to make here: your mortgage rate is decided by your mortgage lender, not the MPC.

Changes in the base rate will clearly affect the sentiment around the direction mortgage rates are going, but they do not always directly force your lender to change your own mortgage rate in turn (although there are exceptions, discussed below).

In fact, the base rate can even move in the opposite direction to mortgage rates. These contradictions are caused by market expectations moving one way and events pulling rates in the opposite direction.

So what are the key factors influencing lenders when setting mortgage interest rates? That is the question this guide will answer, by “following the money” from global economic shocks to the rate on your own offer letter.

Which rate are you on?

When you hear that “rates have gone up” or “rates are expected to fall”, you need to know which rate you are paying, and which type of mortgage you are on, to understand the effect on your pocket.

Fixed rate mortgages

The vast majority of UK mortgages – an average of 91% over the last 10 years – are on a fixed term, fixed rate deal. Known as a “fix”, these deals lock borrowers in to repay the lender at a fixed interest rate for a set period of time e.g. 2, 3, 5 or even 10 years.

The rate is 100% guaranteed and will be unaffected by any changes to the base rate or any external factors. The key benefit is certainty – you will know exactly what your monthly payments are on your mortgage for the length of the deal. The downside is that if rates fall, your payments stay the same. At the end of the fixed term, a remortgage needs to be arranged to cover the outstanding balance of the loan.

Beware of “eye catching” deals

The devil is in the detail in fixed rates as your “headline rate” may not always represent the total cost of your loan. Lenders often apply fees to the loan, such that a 3.9% rate with a £1,999 fee can cost more over two years than a 4.2% rate with no fee (depending on loan size). Lenders adjust the rate-and-fee mix to catch your eye on best-buy tables, so remember to compare on total cost (or “true cost”) and speak to your broker before committing.

Variable rate mortgages

The remaining 9% of mortgages are on “variable” rates, meaning your monthly payments can go up or down at any time and can be affected by changes in the UK base rate and/or other factors discussed below. These include:

1.  Borrowers on their lender’s Standard Variable Rate (SVR). SVRs are the “default” rates set by mortgage lenders when you do not accept their remortgage offer or move to another lender at the end of your fixed term deal. They are often eye-wateringly expensive in comparison to any other rate and are generally to be avoided wherever possible.
2. Borrowers on a “tracker” rate. When you are on a tracker, the interest rate that you pay “tracks” an external benchmark — usually the BoE Bank Rate – plus an extra percentage set by your lender.
3. Borrowers on a “discount” rate. Discount mortgages are variable, and set at a fixed margin (say 2%) below SVR for a fixed period such as 2 years. They work for people who are comfortable with variable interest rates, and expect interest rates to fall or stay stable.

The global economic backdrop

The key factor in setting the UK base rate is inflation. The BoE has a mandate to manage inflation for the long-term health of the economy and the MPC, although independent, keeps that as its overarching priority. When the economy “overheats” with prices and wages rising in tandem, the Bank often looks to the “big lever” of an interest rate rise to “cool” economic activity and “tame” inflation.

But as we all know to our cost, inflation is affected by numerous external factors, most of which are beyond the reach of the suited economists on the Monetary Policy Committee.

War causes the biggest shock to energy prices, which feed directly into consumer inflation. The Russian invasion of Ukraine led to gas prices spiking to terrifying new highs, which in turn saw a costly intervention by the UK government to cap them for our citizens.

The US/Israeli attack on Iran led to the disruption of the Strait of Hormuz, a globally significant shipping lane. This led to an oil price rise that immediately impacted fuel prices, which in turn increased distribution costs hitting economies worldwide. Further food price shocks are already “in the post” as fertiliser (another key commodity going through the Strait) prices have risen, and so the inflationary spiral continues…

Both of these conflicts are ongoing, as is the heightened tension throughout the Middle East. This causes global economic instability that has further knock-on effects on bond markets and interest rates worldwide.

Our rates are, of course, set independently to the US and Eurozone. However, the way these huge economies (and their respective base rates) are trending, will always affect our own direction of travel, even if we have no control over them.

“Trumpflation” is another example of “rogue” political activity, in the form of international tariffs and aggressive policies towards key trading partners such as Canada. This has a direct effect on US inflation which will ultimately push up US rates (as long as the Federal Reserve remains independent).

Why independence matters

Global capital markets lend money to governments (see the gilt section below) and to the banks that ultimately fund your mortgage.

These markets know that rate rises are often necessary to tame inflation, but are rarely popular with politicians, voters, businesses or consumers. One exception here is that a higher base rate gradually feeds into savings interest rates, popular with those with cash accounts such as ISAs. However, if inflation is also simultaneously higher, that eats into the value of any gains.

So the rate setting function in the UK, US and EU is deliberately independent of government. Our mechanism is called the Monetary Policy Committee (MPC), made up of economists with a range of views. The US equivalent is the Federal Open Market Committee (FOMC).

Two aspects of rate setting by these committees that have a calming effect on markets are the transparency of voting (to hold, raise or cut rates) and the detailed forward guidance offered by central banks. Minutes of the rate setting committees – in our case the MPC – are published alongside commentary weighing up the various factors going into the decision. This makes it possible to read the balance between “hawks” (members who tend to vote to keep rates high) and “doves” (those who prefer to bring rates down wherever possible) in any given meeting. Consequently, rate changes are rarely a huge surprise to markets.

In both cases a proportion of members (a slight majority in the US, a slight minority in the UK) are appointed by the government or Chancellor of the day, which obviously has a major influence. However, if markets no longer believe in the genuine independence of these committees – severely tested by Donald Trump recently – they will sell off that government’s debt, causing yields to rise and making state debt ever harder to pay off.

Sovereign debt and how bond markets can put pressure on governments

Government borrowing (aka sovereign debt) is required to finance what is commonly referred to as “the deficit”, or the gap between the state’s annual income and outgoings. The scale of government borrowing is often measured in comparison to a nation’s Gross Domestic Product (the total of all economic activity in one year). In the UK the debt to GDP ratio for 2025 was 94% and fairly stable, in the US it is 123% and distinctly growing.

As governments issue bonds (known as “gilts” in the UK and “treasuries” in the US), the investor market determines their overall value in relation to the risk of default, known as the “yield”. When you hear that “yields have risen” that means that governments have to pay more to service their debt, which is likely to be politically painful.

Yields are also closely linked to the direction of base rates – as one rises or falls, the other will often follow, which is particularly awkward in an inflationary situation. If rising inflation causes the central bank (in our case, the Bank of England) to raise rates, it is likely to lead to higher yields and, in turn, hamper the government’s ability to stimulate the economy.

Rate expectations: the role of swaps

Interest rate “swaps” are short to medium term contracts (known as “derivatives”) that UK banks and building societies take out to manage the risk of base rates moving during the fixed term mortgage deals they offer their customers. The swaps market reflects day-by-day (sometimes minute by minute) shifts in how markets read inflation, national and global economic stability, security and growth, all of which feed into rate expectations.

Swap rates reflect where markets expect the base rate to be over the life of the fixed mortgage deal. The swap rate is a forward indicator, meaning that it anticipates rate changes rather than reflects them after the fact. Lenders add a margin to the swap rate to cover costs, risk and profit, which is why a five-year fixed rate mortgage might sit around half a percentage point above the five-year swap contract.

The UK base rate was held at 3.75% throughout 2026 so far, but 2-year fixed mortgage rates sit at 5.06% on average as of writing in September 2026 (up from 4.25% before the Iran conflict started). Much of the difference is attributable to forward expectations of rate hikes. The market is speculating a series of rate rises as a response to global inflationary pressures.

It’s through this mechanism that fixed rates are largely priced. The main driver of swap rates is market expectation, not the last MPC decision. Movements in the base rate do affect sentiment (rather than lenders directly) but by the time the central bank changes the base rate, swap rates have usually priced the change in.

Political upheaval and the public finances

Politics and politicians are another key factor influencing both the base rate and your mortgage rate. If the government of the day is perceived to have “fiscal credibility” (the knack of balancing the budget without adding dramatically to the deficit) it will tame gilt yields over time. Gilt yields feed into swap rates, directly affecting fixed rate mortgages.

This can also work in reverse. Consider the sorry tale of the Liz Truss “mini-budget” of 2022. As the former Prime Minister and her Chancellor Kwasi Kwarteng announced unfunded tax cuts, the bond markets tanked. This pushed up yields dramatically and had a vicious knock-on effect on the “swaps” market, which “hedges” (de-risks) most of the UK’s fixed-term mortgages. As a result of the spike in swap rates, “Trussonomics” resulted in an immediate 1-2% rise in mortgage rates and a massive cull of the mortgages on the market as lenders pulled fixed-rate deals that they could no longer afford to offer.

This happened in a matter of days and demonstrates that lenders often move to reprice their loans well in advance of any changes in base rate.

Fiscal credibility and hair-trigger market reactions

The Truss mini-budget has left a lasting mark. Gilt markets remain sensitive to any sign of UK politicians overspending relative to the tax take, and that sensitivity feeds through into swap rates and therefore mortgage pricing.

Recent events, such as the abrupt changing of the guard at 10 Downing Street and an intense focus on Andy Burnham’s own fiscal credibility, have seen gilt markets twitch nervously. This makes life very difficult for the new Prime Minister and Chancellor and adds more pressure on budgets as the cost of government debt spikes.

Market sentiment is not the whole story

All of the factors discussed above ultimately feed into the intangible “vibe” that is market sentiment. The market isn’t a person but it is assumed to have feelings and it certainly has expectations, and the combined direction of travel of these factors affects how it “feels”.

But as well as our national economic performance, inflationary pressures, global instability, deficit management, gilt yields and swap rates there are two further sets of factors that affect the rate you pay for your mortgage: the lender and you.

How lenders affect rates

What it costs a lender to raise money sets the floor for its mortgage rates and every type of lender has access to a specific source of money at a specific cost.

High street banks lend cheap customer deposits, building societies rely on savers, and specialist lenders borrow on the wholesale markets, which is why their rates can move faster.

Regulation adds to the cost: affordability rules, caps on income multiples and the capital requirements banks face all feed into what you pay.

Competition pulls the other way. Price wars and challengers chasing market share can push rates below what funding costs justify. Be aware, though, that rates tend to rise faster than they fall: lenders reprice upwards within days of swap rates jumping, but wait to see a fall hold before passing it on. Critics say that rates go up like a rocket, but fall like a feather.

The role of lender performance against targets

Whatever type of financial institution they are, individual lenders will all have different annual goals. These include:

• Total amount lent out
• Volume of customers in different segments (e.g. to first time buyers, BTL etc.)
• Margins on their different products (fixes, trackers etc)
• Proportion of remortgage offers taken up relative to their loan book
• Market share
• Overall profitability

These goals will be broken down into quarterly and monthly targets, but the housing market is both traditionally seasonal and notoriously affected by many of the external factors listed above, as well as stamp duty rates and house prices. This makes predicting performance difficult and lenders can find themselves falling short against expectations. In these circumstances management will act to correct the course.

Lenders will flex their rates and vary product terms in order to fill pipelines and hit targets. They compete hardest (to retain volume) when a wave of fixed deals is ending at once. This sometimes means cutting rates (even when bucking the trend of the market) but equally lenders can act to throttle demand and withdraw deals. For example, if they have exceeded their volume targets in the first 3 quarters, they can afford to focus on profitability rather than price wars, taking on only the most attractive business in terms of security and customer profile.

Which brings us on to…

You and your mortgage

The final set of factors governing your precise mortgage offer are personal to you. These all determine the level of risk the lender is willing to take, and therefore the amount lent and interest rate it is prepared to offer. Details required from both you and any partner named on the mortgage include your:

• Age
• Contract day rate or annual income
• Cash deposit (or equity in your property)
• Credit history
• Financial commitments
• The regularity and security of your employment
• The type and complexity of your income (Ltd company contractor, umbrella contractor, CIS)
• The age and type of property
• The cost or value of your property relative to your neighbourhood

Buy-to-let mortgages will also take into account rental cover, portfolio status and ownership structure.

So you can see that while it all boils down to a single number, the interest rate you pay is affected by events far from home and circumstances unique to you and your home.

Taking out a mortgage may be the biggest financial decision you ever make, which is why it pays to speak to an independent broker able to give you genuinely impartial advice. Speak to a mortgage expert here.