Compare Mortgage Overpayment Plans - Preview the Advanced Mortgage Planner
Model overpayments, a fixed rate ending and up to 3 plans side by side, with a year-by-year schedule.
Below is a fully worked example with fixed figures, not yours, showing what the planner produces.
Results are estimates only and not financial advice
Advanced Mortgage Planner: £14.99 one-off payment, no subscription.
- The Advanced Mortgage Planner provides informational estimates only and does not guarantee savings or results.
At checkout you will be asked to tick a box that says: “I want access to the Advanced Mortgage Planner to start immediately, before the 14-day cancellation period ends. I understand that I waive my right to cancel once access has started, and that refunds are not offered once access has been granted, unless required by law. Refund policy”
Worked example: a fixed rate ending, three plans compared
These are example figures, calculated as of September 2026. With the planner you enter your own.
- Mortgage balance
- £250,000
- Interest rate
- 4.5% until Sep 2028, then 5.25%
- Remaining term
- 25 yrs
- Mortgage anniversary month
- Not set (years counted from today)
- Plan A
- £100 a month and a £2,500 lump sum in Sep 2028
- Plan B
- £300 a month
- Plan C
- £1,000 a month
Plans side by side
| Figure | No overpayments | Plan A: £100 a month and a £2,500 lump sum | Plan B: £300 a month | Plan C: £1,000 a month |
|---|---|---|---|---|
| Monthly overpayment | £0 | £100 | £300 | £1,000 |
| Lump sums | None | £2,500 in Sep 2028 | None | None |
| Contractual payment now | £1,389.58 | £1,389.58 | £1,389.58 | £1,389.58 |
| Payment after the fixed rate ends | £1,491.11 from Oct 2028 | £1,485.31 from Oct 2028 | £1,484.17 from Oct 2028 | £1,474.92 from Oct 2028 |
| Mortgage-free | Sep 2051 | Jul 2048 | Sep 2044 | Oct 2037 |
| Time saved | — | 3 yrs 2 mths | 7 yrs | 13 yrs 11 mths |
| Total interest | £194,897 | £164,179 | £132,460 | £76,172 |
| Interest saved | — | £30,718 | £62,437 | £118,725 |
| 10% allowance check | No overpayments | Within a typical 10% allowance in every mortgage year | Above a typical 10% allowance in 1 mortgage year (year 18) | Above a typical 10% allowance in 4 mortgage years (years 8, 9, 10, 11) |
This is lender-specific, not a fixed industry rule — always check your mortgage offer document or ask directly.
The payment after the fixed rate ends assumes your lender recalculates it at the rate you enter, over the shorter term your overpayments have earned. Some lenders will recalculate and lower your monthly payment instead, and some only do this if you ask, so check your mortgage offer or ask your lender how your overpayments will be applied.
Balance over time
Grey dashes: no overpayments. Solid green line: Plan A: £100 a month and a £2,500 lump sum. Long dashes: Plan B: £300 a month. Dotted line: Plan C: £1,000 a month. The thin vertical line marks the end of the fixed rate. The dates under the chart are when each balance reaches zero.
Plan details: Plan A: £100 a month and a £2,500 lump sum
The planner shows these details for each plan. Here they are for Plan A.
Where each year's money goes
Plan A: £100 a month and a £2,500 lump sum. Each bar is one mortgage year: principal at the bottom, interest on top.
The home stretch
Milestones with this plan. The pale band is the time you no longer pay.
- TodaySep 2026
- 25% paid offAug 2034
- Half paid offJun 2040
- 75% paid offNov 2044
- Mortgage-freeJul 2048
- 3 yrs 2 mths sooner
- Without overpayingSep 2051
| Year | Payments | Balance at the start | 10% allowance | Overpaid | Check |
|---|---|---|---|---|---|
| 1 | Oct 2026 – Sep 2027 | £250,000 | £25,000 | £1,200 | Within |
| 2 | Oct 2027 – Sep 2028 | £243,237 | £24,324 | £3,700 | Within |
| 3 | Oct 2028 – Sep 2029 | £233,663 | £23,366 | £1,200 | Within |
| 4 | Oct 2029 – Sep 2030 | £226,741 | £22,674 | £1,200 | Within |
| 5 | Oct 2030 – Sep 2031 | £219,448 | £21,945 | £1,200 | Within |
| 6 | Oct 2031 – Sep 2032 | £211,762 | £21,176 | £1,200 | Within |
| 7 | Oct 2032 – Sep 2033 | £203,662 | £20,366 | £1,200 | Within |
| 8 | Oct 2033 – Sep 2034 | £195,128 | £19,513 | £1,200 | Within |
| 9 | Oct 2034 – Sep 2035 | £186,134 | £18,613 | £1,200 | Within |
| 10 | Oct 2035 – Sep 2036 | £176,656 | £17,666 | £1,200 | Within |
| 11 | Oct 2036 – Sep 2037 | £166,669 | £16,667 | £1,200 | Within |
| 12 | Oct 2037 – Sep 2038 | £156,144 | £15,614 | £1,200 | Within |
| 13 | Oct 2038 – Sep 2039 | £145,054 | £14,505 | £1,200 | Within |
| 14 | Oct 2039 – Sep 2040 | £133,367 | £13,337 | £1,200 | Within |
| 15 | Oct 2040 – Sep 2041 | £121,051 | £12,105 | £1,200 | Within |
| 16 | Oct 2041 – Sep 2042 | £108,073 | £10,807 | £1,200 | Within |
| 17 | Oct 2042 – Sep 2043 | £94,398 | £9,440 | £1,200 | Within |
| 18 | Oct 2043 – Sep 2044 | £79,986 | £7,999 | £1,200 | Within |
| 19 | Oct 2044 – Sep 2045 | £64,800 | £6,480 | £1,200 | Within |
| 20 | Oct 2045 – Sep 2046 | £48,797 | £4,880 | £1,200 | Within |
| 21 | Oct 2046 – Sep 2047 | £31,933 | £3,193 | £1,200 | Within |
| 22 | Oct 2047 – Jul 2048 | £14,162 | £1,416 | £900 | Within |
This is lender-specific, not a fixed industry rule — always check your mortgage offer document or ask directly.
Some lenders allow more than 10%, and some lenders remove the limit once the fixed rate ends, so check your mortgage offer or ask your lender.
The 10% allowance check doesn't include overpayments you've already made this mortgage year, so you may have used more of your allowance than it shows.
Mortgage years counted from today. Add your anniversary month for a closer match to your lender.
Show the year-by-year schedule
| Year | Payments | Balance at year end | Principal (year) | Interest (year) | Principal (to date) | Interest (to date) |
|---|---|---|---|---|---|---|
| 1 | Oct 2026 – Sep 2027 | £243,237 | £6,763 | £11,112 | £6,763 | £11,112 |
| 2 | Oct 2027 – Sep 2028 | £233,663 | £9,574 | £10,801 | £16,337 | £21,913 |
| 3 | Oct 2028 – Sep 2029 | £226,741 | £6,921 | £12,102 | £23,259 | £34,015 |
| 4 | Oct 2029 – Sep 2030 | £219,448 | £7,294 | £11,730 | £30,552 | £45,745 |
| 5 | Oct 2030 – Sep 2031 | £211,762 | £7,686 | £11,338 | £38,238 | £57,083 |
| 6 | Oct 2031 – Sep 2032 | £203,662 | £8,099 | £10,924 | £46,338 | £68,007 |
| 7 | Oct 2032 – Sep 2033 | £195,128 | £8,535 | £10,489 | £54,872 | £78,496 |
| 8 | Oct 2033 – Sep 2034 | £186,134 | £8,994 | £10,030 | £63,866 | £88,526 |
| 9 | Oct 2034 – Sep 2035 | £176,656 | £9,478 | £9,546 | £73,344 | £98,072 |
| 10 | Oct 2035 – Sep 2036 | £166,669 | £9,987 | £9,036 | £83,331 | £107,108 |
| 11 | Oct 2036 – Sep 2037 | £156,144 | £10,524 | £8,499 | £93,856 | £115,608 |
| 12 | Oct 2037 – Sep 2038 | £145,054 | £11,090 | £7,933 | £104,946 | £123,541 |
| 13 | Oct 2038 – Sep 2039 | £133,367 | £11,687 | £7,337 | £116,633 | £130,878 |
| 14 | Oct 2039 – Sep 2040 | £121,051 | £12,316 | £6,708 | £128,949 | £137,586 |
| 15 | Oct 2040 – Sep 2041 | £108,073 | £12,978 | £6,046 | £141,927 | £143,632 |
| 16 | Oct 2041 – Sep 2042 | £94,398 | £13,676 | £5,348 | £155,602 | £148,980 |
| 17 | Oct 2042 – Sep 2043 | £79,986 | £14,411 | £4,612 | £170,014 | £153,592 |
| 18 | Oct 2043 – Sep 2044 | £64,800 | £15,186 | £3,837 | £185,200 | £157,429 |
| 19 | Oct 2044 – Sep 2045 | £48,797 | £16,003 | £3,021 | £201,203 | £160,450 |
| 20 | Oct 2045 – Sep 2046 | £31,933 | £16,864 | £2,160 | £218,067 | £162,610 |
| 21 | Oct 2046 – Sep 2047 | £14,162 | £17,771 | £1,253 | £235,838 | £163,863 |
| 22 | Oct 2047 – Jul 2048 | £0 | £14,162 | £316 | £250,000 | £164,179 |
"Year" columns are what you pay during that mortgage year. "To date" columns are the running totals from today.
This calculator does not account for lender terms, fees or early repayment charges.
Overpaying beyond that allowance can trigger an Early Repayment Charge (ERC). This can significantly reduce or even eliminate the interest savings from overpaying.
- Results are estimates only and do not constitute financial advice. Actual mortgage terms and savings will vary.
- Your home may be repossessed if you do not keep up repayments on your mortgage.
- The Advanced Mortgage Planner provides informational estimates only and does not guarantee savings or results.
At checkout you will be asked to tick a box that says: “I want access to the Advanced Mortgage Planner to start immediately, before the 14-day cancellation period ends. I understand that I waive my right to cancel once access has started, and that refunds are not offered once access has been granted, unless required by law. Refund policy”
See How Overpayments, a Fixed Rate Ending & Time Could Affect a Mortgage
The planner shows how different overpayment plans compare, including what happens when your fixed rate ends, using the rate you enter.
What the planner does:
- Model what happens when your fixed rate ends, using the new rate you enter
- Add up to 5 lump sums, each in the month you choose
- Compare up to 3 overpayment plans side by side
- Check every mortgage year of each plan against a typical 10% allowance
- See a year-by-year schedule with annual and running totals
- Compare your plans on a balance chart, with interest vs principal and the home stretch for each plan
With the planner you enter your own figures and plans.
Advanced Mortgage Planner: £14.99 one-off payment, no subscription.
- The Advanced Mortgage Planner provides informational estimates only and does not guarantee savings or results.
At checkout you will be asked to tick a box that says: “I want access to the Advanced Mortgage Planner to start immediately, before the 14-day cancellation period ends. I understand that I waive my right to cancel once access has started, and that refunds are not offered once access has been granted, unless required by law. Refund policy”