What a fixed rate actually does.
No product names, nothing to buy. Just how the thing you already have behaves — because almost every difficult property decision turns out to be a mortgage decision.
Your fixed rate is a short deal on a long loan
A twenty-five year mortgage is almost never priced for twenty-five years. You buy a rate for two, three or five, and when it runs out the loan carries on — at whatever rate applies then.
This is the part most calculators get wrong. They take the rate you’re paying now and run it to the end of the term, which produces a number that was never going to happen. It makes the future look calmer than it is.
The date your fixed rate ends is on your mortgage offer. It is the single most useful date you own, and most people can’t name it.
Three numbers, and only one of them is the rate
Change any one and the payment moves. People watch the rate and ignore the other two, which is why the answer often surprises them.
The balance
What’s left to repay. Lower than when you started, which works in your favour — a higher rate on a smaller debt is not the disaster it sounds like.
The rate
What it costs to borrow. The number everyone watches, and the only one you can’t control.
The years remaining
How long you have to repay it. Shorter means higher payments, because the same debt is squeezed into less time. This is the one people forget.
Which is why the arithmetic has to be yours. Two people facing the same rate rise can land in completely different places, because one is eight years into a twenty-five year term and the other is nineteen.
The same rise, two borrowers
Both fixed £250,000 at 2.6% in 2022. Both move to 5.6%. One took twenty-five years, the other took fifteen.
The person with the longer term pays less each month and far more in total. The one with the shorter term takes the bigger monthly hit and is nearly halfway through the debt. Neither is wrong. They are different positions, and a national average describes neither.
Illustration on a rate you chose. Not a forecast, not a recommendation.
Early on, most of your payment is interest
A repayment mortgage doesn’t chip away evenly. Interest is charged on what you still owe, so in the first years the bank takes most of the payment and the debt barely moves. Later it flips. Nothing is wrong; that is simply how the arithmetic falls.
Year three
Roughly two-thirds of each payment is interest. The balance is going down slowly and it can feel like nothing is happening.
Year twelve
The split is close to even. This is usually the point people notice the balance moving.
Year twenty
Most of the payment is now capital. The debt falls fast, which is why overpaying late in a term does less than people expect.
Four things that catch people out
The standard rate is the default, not the plan
If you do nothing when a fix ends, you move to the lender’s standard variable rate, which is usually the most expensive option available. Doing nothing is a decision.
Overpayments are usually capped
Most fixed deals allow around 10% of the balance a year before a charge applies. The cap is in your offer, and it changes whether overpaying is even possible.
Leaving early costs money
An early repayment charge is a percentage of the balance, and it often steps down each year of the fix. Selling or remortgaging mid-deal has a price attached.
Interest-only doesn’t repay anything
The payment covers interest and nothing else, so the balance at the end is the balance you started with. That is fine if there is a plan for it, and expensive if there isn’t.
All four are in your paperwork. Drop the mortgage offer into Bernwy and the dates, the caps and the charges come out of it, so you stop having to remember them.