Your mortgage has dates that cost you money.
Here they all are.
Nobody is paid to remind you of these dates, because there is no commission in any of them. So here is the complete list. Every date on a fixed-rate mortgage that can cost you real money, or save it, explained in plain English.
1 · The day your fix ends
When your fixed deal ends and you do nothing, you don't keep your rate. You fall onto your lender's Standard Variable Rate (SVR), which is usually 2 to 3 percentage points higher. On a £200,000 balance that is commonly a jump of several hundred pounds a month — the payment shock that catches most people off guard, since it lands whether or not you noticed the date coming. Your lender will write to you about it close to the date, in their own time. Put the real date somewhere you will see it.
2 · Six months before: your lock window
Most lenders let you secure a new deal up to six months ahead while keeping your current one until it ends. Many also let you reselect if rates fall before your fix ends, so securing early means a later rise won't change the deal you've locked. The exact rules — and whether there is any cost — vary by lender. The window opens on a specific date, and most people miss it.
3 · Your early-repayment charge step-downs
Leave a fixed deal early and you pay an early repayment charge (ERC), which is a percentage of your balance. The part everyone forgets is that the percentage usually steps down each year: 5%, then 4%, then 3%, and so on. The exact day yours drops is written in your mortgage offer, and it can flip the whole leave-or-stay calculation overnight. Our calculator works this out month by month, including the day the answer changes.
4 · Your overpayment allowance reset
Most fixed deals let you overpay 10% of the balance each year without any charge. The allowance resets on a date. For some lenders that is your deal anniversary, for others it is 1 January. Whatever you don't use does not roll over, so if you have spare cash, the reset date is when the clock starts again.
5 · The day the break-even maths flips
Whether leaving your fix is worth it depends on three moving parts: the rate you could switch to, the charge you would pay today, and the time left on your deal. All three keep changing, so the answer does too. There is an exact day when "not worth it" becomes "worth it". We calculate it for free, and for a few pounds we will watch it for you and email you if it moves.
What to do with all this
- Run your numbers through the calculator. It is free, takes two minutes, and stores nothing.
- If you prefer to look before you type, see a full worked example first.
- If you want advice on your options, speak to an adviser regulated by the FCA, and take the numbers with you.
Frequently asked questions
What happens if I do nothing when my fixed mortgage ends?
You move onto your lender's Standard Variable Rate (SVR), usually 2 to 3 percentage points higher than a typical fixed rate. On a £200,000 balance that is commonly several hundred pounds more a month, and it starts from the day your fix ends, not from whenever you notice.
How early can I lock in my next mortgage deal?
Most lenders let you secure a new deal up to six months before your current one ends, while you keep your existing rate until then. Many also let you reselect if a better rate appears before the new deal starts. Rules vary by lender, so check yours.
Does my early repayment charge stay the same the whole way through my deal?
No. It is a percentage of your balance that steps down each year you are into the deal, for example 5%, then 4%, then 3%. The date each step-down lands is written in your mortgage offer, and it can change the cost of leaving by thousands overnight.
How much can I overpay without being charged?
Most fixed deals let you overpay 10% of the balance each year with no charge. The allowance resets on a date set by your lender, and whatever you do not use does not carry over to the next year.
Is there ever an exact day when breaking my fix becomes worth it?
Yes. The answer depends on your early repayment charge, the rate you could switch to, and the time left on your deal, and all three change over time. Because your charge steps down on a known date, there is often a specific day when the sum flips from not worth it to worth it.
Should I remortgage now, or wait?
There is no single answer — it depends on your fix's end date, your ERC schedule, and the rate you could move to today, and all three keep changing. Rather than following a general rule, run your specific numbers through the calculator to see the date the answer flips for your mortgage.
Is a 2-year fix or a 5-year fix better?
It depends on what you're trading off. A shorter fix costs less in early repayment charges if you need to leave early or rates fall further; a longer fix trades that flexibility for payment certainty. Compare the live 2-year and 5-year averages on the homepage, then run your own numbers to see what switching would actually cost or save you.
Can I port my mortgage instead of remortgaging when I move?
Often, yes. Porting means keeping your existing rate and deal when you move home, rather than paying an early repayment charge to start a new one elsewhere — subject to a fresh affordability check and the lender accepting the new property. Whether it's actually cheaper than breaking and remortgaging depends on the ERC, the fees involved, and how the numbers compare over your remaining term.