Share Incentive Plan Calculator
Estimate what a UK Share Incentive Plan (SIP) could be worth: your partnership contribution, employer matching, free shares, the Income Tax and National Insurance you could save, and what happens if you withdraw early. Free, no sign-up, calculated entirely in your browser.
- ✓ Covers free, partnership, matching and dividend shares
- ✓ Flags the tax outcome at the 3-year and 5-year holding marks
- ✓ Nothing you type is stored or sent anywhere
A single-page view of your SIP
This calculator brings together the three moving parts of a UK Share Incentive Plan — what you contribute, what your employer adds on top, and what the tax treatment looks like depending on how long you hold the shares — into one estimate. It's built for a quick "is this worth it" check, not a personalised financial plan.
Real shares, held in trust
A SIP is one of four HMRC tax-advantaged UK share schemes. Rather than an option to buy shares later (as with SAYE), a SIP gives you real shares now, held inside a trust set up by your employer. You're the beneficial owner throughout — the trust exists to administer the scheme's holding-period rules, not to control your shares. Read the full guide: What Is a Share Incentive Plan?
A plan can combine up to four share types
Not every employer offers all four — check your own plan to see which apply to you.
Free Shares
Up to £3,600/yearAwarded by your employer at no cost to you — can be linked to performance measures applied consistently.
Partnership Shares
Up to £1,800/year or 10% of salaryBought by you from gross salary — before Income Tax and NIC are deducted.
Matching Shares
Up to 2 per partnership shareFree shares your employer adds for every partnership share you buy, at a ratio they choose.
Dividend Shares
No statutory capDividends on your SIP shares reinvested into further shares, instead of taken as cash.
Where the tax saving actually comes from
Partnership shares are bought from your gross pay, so you don't pay Income Tax or employee National Insurance on the amount you contribute at the point of purchase. Free and matching shares cost you nothing, so their full value arrives without any Income Tax or NIC at the point of award — unlike an equivalent cash bonus, which would be taxed in full.
The biggest lever, though, is time: shares held in the plan for 5 years or more can generally be withdrawn completely free of Income Tax and National Insurance, no matter how much they've grown. Full detail and worked examples: SIP Tax Benefits Explained and the SIP Tax Savings Calculator.
What happens at 3 years and 5 years
Full tax may apply
Income Tax and NIC generally due on market value at removal.
Reduced tax may apply
Tax on the lower of value at award vs. value at removal.
Generally tax-free
No Income Tax or NIC due on withdrawal from the plan.
Check your own likely outcome with the SIP Holding Period Calculator, or read the full rules in SIP Holding Period Rules: What Happens After 3 and 5 Years?
A £35,000 salary, £100/month contribution
An employee earning £35,000 contributes £100/month (£1,200/year) in partnership shares — under both the £1,800 flat cap and the 10%-of-salary cap (£3,500), so the full amount goes through. Their employer matches 1:1, adding another £1,200/year in matching shares, and separately awards £600 of free shares that year.
| Component | Annual value |
|---|---|
| Partnership shares (from gross salary) | £1,200 |
| Matching shares (1:1) | £1,200 |
| Free shares | £600 |
| Total annual award value | £3,000 |
Because the £1,200 partnership contribution came from gross pay, this employee also avoided Income Tax and NIC on that £1,200 at the point of contribution. Try your own numbers in the calculator above, or the dedicated SIP Tax Savings Calculator.
Three steps
- Enter your salary and planned monthly contribution. The calculator applies the £1,800 and 10%-of-salary caps automatically.
- Set your employer's matching ratio and free shares, if offered. Check your own SIP invitation for these figures.
- Choose a holding period to see the likely tax outcome. Use the dedicated Holding Period Calculator for a specific award date.
What this calculator doesn't do
It doesn't know your specific employer's plan rules, doesn't account for Capital Gains Tax on growth after shares leave the trust, and the growth rate is an assumption you choose — not a forecast. It's a starting point for understanding your SIP, not a substitute for checking your own plan documentation or speaking to a qualified adviser.
Frequently asked questions
Is this an official HMRC calculator?
No. This is an independent educational tool, not affiliated with HMRC or any government body. Figures are based on our understanding of current HMRC guidance — see our methodology.
Do I have to join my employer's SIP?
No — participation involving partnership shares is voluntary since it involves a deduction from your own pay. Free share awards may be automatic for eligible employees depending on the plan.
Is there a lifetime limit on how much I can hold in a SIP?
No statutory lifetime cap exists — the £3,600/£1,800/2:1 figures are annual award limits, not caps on total value held.
What happens if I leave my job before 5 years?
It depends on your reason for leaving and your specific plan's "good leaver" provisions. See our guide on holding period rules for the general position.
Look at one part of your SIP in more detail
SIP Tax Savings Calculator
Isolate exactly how much Income Tax and NIC your partnership contribution saves.
Open calculator → ContributionsPartnership Shares Calculator
See which cap — £1,800 or 10% of salary — applies to you.
Open calculator → WithdrawalHolding Period Calculator
Check the likely tax outcome if you withdrew shares today.
Open calculator →- HMRC, Employee Tax Advantaged Share Scheme User Manual (ETASSUM) — Share Incentive Plans
- Income Tax (Earnings and Pensions) Act 2003, Schedule 2
- GOV.UK guidance on tax and employee share schemes
- HMRC Capital Gains Manual, CG56490 — Share Incentive Plan (SIP): introduction