Share Incentive PlanCalculator
Model your SIP contributions, employer matching, tax-free benefits and projected wealth — all in one powerful tool.
Share Incentive Plan Calculator
Enter your details below to calculate your SIP contributions, employer matching, tax savings, and projected portfolio value.
Your SIP Projection
Results update instantly as you adjust the inputs above
Frequently Asked Questions
Everything you need to know about Share Incentive Plans — from tax rules to employer matching, answered in plain English.
The Complete Guide to Share Incentive Plans: How to Maximise Your SIP in 2024
Most employees enrolled in a Share Incentive Plan are leaving substantial money on the table. Here is everything you need to know to get the most from yours — including the tax tricks your payroll department probably forgot to mention.
If your employer offers a Share Incentive Plan and you are not fully using it, you are essentially saying no to a pay rise. That is not an exaggeration. Between the tax relief on contributions, the National Insurance savings, and the employer-matched shares that arrive at no cost to you, a well-run SIP can generate returns that no cash ISA or market fund can reliably match in the short term — purely from the structural advantages before the share price has moved at all.
What is a Share Incentive Plan, really?
A Share Incentive Plan is an HMRC-approved employee share scheme governed by Schedule 2 of the Income Tax (Earnings and Pensions) Act 2003. The practical upshot is simple: it is a legally protected wrapper that lets you and your employer move money into company shares with extraordinary tax efficiency.
There are four distinct elements that can exist within a single SIP, though employers are not required to offer all four:
The maths behind the free money
Let us put real numbers to a realistic scenario. Suppose you earn £45,000 and contribute the maximum £1,800 in partnership shares. Your employer offers a 1:1 match and awards £3,000 in free shares.
| Item | Value | Notes |
|---|---|---|
| Partnership shares purchased | £1,800 | Deducted pre-tax |
| Income tax saved (20%) | £360 | At source |
| NI saved (12%) | £216 | Immediate saving |
| Actual take-home cost | £1,224 | What you really paid |
| Matching shares received | £1,800 | Free from employer |
| Free shares received | £3,000 | Free from employer |
| Total portfolio value | £6,600 | Day one |
| Your real investment | £1,224 | After all reliefs |
| Immediate return | +£5,376 | +439% |
The 5-year rule: why patience is everything
The five-year holding requirement is the engine of the tax benefit. Here is what happens at each stage:
Less than 3 years
Income tax + NI on full market value at withdrawal
3 to 5 years
Income tax + NI on original award value only (growth is tax-free)
5 years or more
Completely tax-free — no income tax, no NI, CGT base cost uplifted
How to use the SIP calculator strategically
Common SIP mistakes that cost employees thousands
- Not contributing the maximum from day one. The compound growth and employer matching lost in year one can never be recouped.
- Withdrawing just before the 5-year mark. A rushed withdrawal triggers a large avoidable tax bill. The difference between 4 years 11 months and 5 years is enormous.
- Ignoring dividend shares. Many SIP participants forget that dividends can be reinvested tax-free. Over five years, even modest dividends compounding inside the SIP add a material amount to the final portfolio.
- Treating it as all-or-nothing. If cash is tight, reduce rather than stop — continuing at a lower level preserves your rolling 5-year timelines and keeps the employer match active.
SIP vs ISA vs Pension: where does it fit in your financial plan?
A SIP is not a replacement for a pension or an ISA — it is a complement. The optimal order for most employees is: (1) maximise employer pension matching first, (2) maximise SIP contributions fully, especially if free and matching shares are on offer, (3) use surplus earnings to contribute to a Stocks and Shares ISA for diversified growth.
Try the Calculator Above
Every salary, every employer match, every tax rate produces a different answer. Enter your own figures in the Share Incentive Plan calculator at the top of this page to see your personalised projection — including the exact tax and NI relief you will receive, your employer’s effective contribution to your wealth, and a year-by-year growth chart.
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