Share Incentive Plan (SIP) Calculator
Calculate your UK Share Incentive Plan (SIP) Income Tax and National Insurance savings, employer matching shares, and total portfolio value after 5 years.
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How to Use the Share Incentive Plan (SIP) Calculator
A UK HMRC-approved Share Incentive Plan (SIP) allows employees to purchase Partnership Shares directly from their gross pre-tax salary (up to £150 per month or £1,800 per year), saving both Income Tax and National Insurance contributions immediately.
Formula and Calculation Methodology
- Partnership Shares: Up to £1,800 per tax year (£150/month) bought from gross pre-tax salary
- Matching Shares: Up to 2 free matching shares for each partnership share (up to £3,600/yr)
- Tax & NI Relief: 28% combined savings for Basic Rate taxpayers (20% Tax + 8% NI) or 42% for Higher Rate (40% Tax + 2% NI)
When your employer also awards Matching Shares (up to a 2:1 ratio) or Free Shares (up to £3,600 per year), your effective return on out-of-pocket cash skyrockets. If you hold your SIP shares inside the plan for at least 5 years, you pay zero Income Tax, zero National Insurance, and zero Capital Gains Tax when withdrawing them.
HMRC Share Incentive Plan (SIP) Annual Allowance & Tax Relief Summary
| SIP Share Component | Annual HMRC Limit | Tax / NI on Award | Tax / NI After 5 Years |
|---|---|---|---|
| Partnership Shares | £1,800 / yr (£150/mo) or 10% salary | 0% (Bought from gross pay) | 0% Income Tax, NI & CGT |
| Matching Shares | Up to 2:1 ratio (£3,600 / yr max) | 0% on award | 0% Income Tax, NI & CGT |
| Free Shares | Up to £3,600 / yr | 0% on award | 0% Income Tax, NI & CGT |
| Dividend Shares | No cap on reinvested SIP dividends | 0% if held 3+ years | 0% Income Tax |
Frequently Asked Questions
How much does £150 a month in a Share Incentive Plan actually cost me?
For a Basic Rate taxpayer (20% Income Tax + 8% Employee NI), £150 per month (£1,800/year) only reduces your take-home pay by £108 per month (£1,296/year). For a Higher Rate taxpayer (40% Tax + 2% NI), it costs just £87 per month (£1,044/year).
What happens if I withdraw SIP shares before 5 years?
If you withdraw shares within 3 years, you pay Income Tax and National Insurance on the market value of the shares at withdrawal. Between 3 and 5 years, you pay tax and NI on the lower of the initial purchase value or current market value. After 5 years, withdrawal is 100% tax-free.
What if I leave my company due to redundancy or retirement?
If you leave for a ‘good leaver’ reason (redundancy, retirement, injury, disability, or TUPE transfer), your SIP shares are immediately exempt from Income Tax and National Insurance even if held for less than 5 years.
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