What This Share Incentive Plan Calculator Estimates
The calculator estimates partnership share contributions, the normal contribution cap, employer matching shares, potential Income Tax and National Insurance savings, projected share value, and the likely tax status based on when shares are removed from the SIP.
How the SIP Tax Estimate Works
Partnership Share Limit
The tool caps annual partnership shares at GBP 1,800 or 10% of salary, whichever is lower.
Tax And NI Saving
Estimated savings are based on your selected Income Tax and National Insurance rates.
Matching Shares
Employer matching is estimated from the ratio you select and the same share price used for partnership shares.
Projected Value
The projection applies your expected annual share growth to partnership and matching shares.
SIP Holding Period Tax Rules
Under 3 years: removing shares can usually create the highest Income Tax and National Insurance risk unless a protected leaver rule applies.
3 to 5 years: some tax advantages may apply, but a tax charge can still arise depending on share type and value.
5+ years: shares kept in a qualifying SIP for 5 years are usually removed free from Income Tax and National Insurance.
Example: GBP 150 Per Month with 1:1 Matching
A common SIP question is whether monthly payroll deductions are worth it once employer matching and tax relief are included. For example, GBP 150 per month equals GBP 1,800 per year, which reaches the normal partnership share cap before any employer matching.
| Annual partnership contribution | GBP 1,800 |
|---|---|
| Estimated 20% Income Tax saving | GBP 360 |
| Estimated 8% NI saving | GBP 144 |
| 1:1 employer matching value | GBP 1,800 |
| First-year benefit before share movement | GBP 2,304 |
Should You Join a Share Incentive Plan?
A SIP may be attractive when you expect to stay long enough to reach the 5-year tax point, your employer offers matching shares, and you are comfortable with company-share risk. Be careful if you may need the money soon, your income changes often, or too much of your savings would depend on one employer stock.
SIP vs SAYE, EMI and LTIP
SIPs are broad employee share plans using payroll deductions and possible matching shares. SAYE is usually an option plan linked to savings. EMI is commonly used by qualifying smaller companies for employee options. LTIPs are often executive or senior employee award plans. The right comparison depends on eligibility, tax treatment, risk, and when shares or options can be accessed.