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Compare projected investment-account balances when you start monthly contributions now or after a chosen delay.
Enter £0–£100,000.00 per month.
Range -100–100 %.
Range 1–100 years; enter whole years.
Range 0–30 years; enter whole years.
Editable sample · change the inputs to model your figures.
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Both schedules use the same monthly contribution and assumed effective annual growth; the delayed schedule contributes for fewer years. Cash outside the account is not included.
The gap is a difference between two modelled investment-account balances, not a guaranteed loss. Consider any cash you may hold, spend or invest elsewhere during the delay.
At the shared horizon, separate total contributions from modelled account growth.
| Scenario | Total contributed | Ending balance | Modelled growth |
|---|---|---|---|
| Start monthly contributions now | £180,000.00 | £588,032.43 | £408,032.43 |
| Start after 5-year delay | £150,000.00 | £393,734.66 | £243,734.66 |
Account balances include modelled growth; contributions exclude any cash held outside the account.
Fixed monthly contributions continue until the shared final horizon; the later-start balance is zero during the delay.
| Year | Start now | After delay | Signed gap |
|---|---|---|---|
| Year 1 | £6,225.15 | £0.00 | £6,225.15 |
| Year 2 | £12,886.06 | £0.00 | £12,886.06 |
| Year 3 | £20,013.23 | £0.00 | £20,013.23 |
| Year 4 | £27,639.30 | £0.00 | £27,639.30 |
| Year 5 | £35,799.20 | £0.00 | £35,799.20 |
| Year 6 | £44,530.30 | £6,225.15 | £38,305.15 |
| Year 7 | £53,872.57 | £12,886.06 | £40,986.51 |
| Year 8 | £63,868.80 | £20,013.23 | £43,855.57 |
| Year 9 | £74,564.76 | £27,639.30 | £46,925.46 |
| Year 10 | £86,009.44 | £35,799.20 | £50,210.24 |
| Year 11 | £98,255.25 | £44,530.30 | £53,724.95 |
| Year 12 | £111,358.27 | £53,872.57 | £57,485.70 |
| Year 13 | £125,378.49 | £63,868.80 | £61,509.69 |
| Year 14 | £140,380.14 | £74,564.76 | £65,815.38 |
| Year 15 | £156,431.90 | £86,009.44 | £70,422.46 |
| Year 16 | £173,607.28 | £98,255.25 | £75,352.03 |
| Year 17 | £191,984.93 | £111,358.27 | £80,626.66 |
| Year 18 | £211,649.03 | £125,378.49 | £86,270.54 |
| Year 19 | £232,689.61 | £140,380.14 | £92,309.47 |
| Year 20 | £255,203.03 | £156,431.90 | £98,771.13 |
| Year 21 | £279,292.39 | £173,607.28 | £105,685.11 |
| Year 22 | £305,068.01 | £191,984.93 | £113,083.08 |
| Year 23 | £332,647.92 | £211,649.03 | £120,998.89 |
| Year 24 | £362,158.42 | £232,689.61 | £129,468.81 |
| Year 25 | £393,734.66 | £255,203.03 | £138,531.63 |
| Year 26 | £427,521.23 | £279,292.39 | £148,228.84 |
| Year 27 | £463,672.87 | £305,068.01 | £158,604.86 |
| Year 28 | £502,355.12 | £332,647.92 | £169,707.20 |
| Year 29 | £543,745.12 | £362,158.42 | £181,586.70 |
| Year 30 | £588,032.43 | £393,734.66 | £194,297.77 |
Recalculates the same contribution schedule at nearby fixed annual rates; each point is the start-now minus delayed ending account balance.
| Annual assumption | Start now ending balance | Delayed ending balance | Signed gap |
|---|---|---|---|
| -3% | £117,842.80 | £104,864.67 | £12,978.13 |
| 2% | £246,037.42 | £194,257.47 | £51,779.95 |
| 7% | £588,032.43 | £393,734.66 | £194,297.77 |
| 12% | £1,540,486.60 | £851,103.29 | £689,383.31 |
| 17% | £4,233,768.09 | £1,910,147.51 | £2,323,620.58 |
Explore how changing a monthly-contribution start date affects a hypothetical UK investment-account projection.
Monthly contributions are added at the start of each modelled month and receive that month's assumed growth. The projection is nominal and excludes tax, charges, inflation and investment volatility. It is not a forecast or personal investment advice. Input ranges and the delay limit appear beside the controls. Website updated 24 October 2026.
These sources support the investing, ISA and risk explanations. The result is a compounding scenario, not a guaranteed return or personal investment advice.