Share Incentive Plan Calculator
Project your Share Incentive Plan (SIP) growth with monthly investing, employer matching, dividends, and estimated tax savings. Estimates only—confirm plan rules and taxes with your employer or advisor.
Projected results
Projected SIP portfolio value
$22,090
Employee contributions
$15,000
Employer contributions
$3,000
Investment gain
$4,090
Employer match benefit
$3,682
Estimated tax savings
$3,000
Estimated only, based on employee contributions and your tax rate input.
Total potential benefit (value + tax savings)
$25,090
How this site’s SIP projection is built
- Each month we add your employee amount plus employer match (match% × employee amount) before applying one month of return—so “P” is always employee + match in the same month.
- Growth and dividend yield are not simply added: we first combine them as an effective annual return (1 + g) × (1 + d) − 1, then convert to a steady monthly rate r = (1 + r_year)^(1/12) − 1 used in the loop.
- “Investment gain” is ending portfolio value minus all dollars you and the employer contributed; it is not the same as taxable gain in a brokerage statement.
- “Employer match benefit” is specific here: ending value with match minus the ending value if only your employee amount were invested each month at the same return assumptions.
- “Estimated tax savings” multiplies total employee contributions by your marginal rate—a rough pre-tax deferral shortcut. It does not model NIIT, AMT, state taxes, or payroll caps.
- Currency amounts are shown in whole U.S. dollars (rounded); very small monthly inputs can round to $0 in the summary tiles.
Math behind the projection
Conceptually this is an ordinary annuity with equal month-end payments and a fixed monthly rate—the same structure as the month-by-month loop the tool runs.
FV = P × ((1 + r)^n − 1) / r
- P = employee monthly + (match% / 100) × employee monthly
- r = (1 + r_year)^(1/12) − 1, where r_year = (1 + g) × (1 + d) − 1 and g, d are your annual inputs as decimals
- n = round(years × 12); investment years are converted to a whole number of months
r_year = (1 + g) × (1 + d) − 1 r = (1 + r_year)^(1/12) − 1
If r is extremely close to zero (both growth and dividend at 0%), the annuity fraction is undefined; the implementation still walks month by month so balances stay intuitive. Negative growth is clamped to −50% annually for stability—treat deep negatives as stress-test only.
Reading the default scenario on this page
The calculator opens with $250/month, 5 years, 20% match, 6% growth and 2% dividend yield. That pairing implies about 8.1% effective annual return before monthlyizing—not the same as typing 8% into a single “return” box elsewhere. Under those defaults you should see employer dollars flowing in every month, a larger ending balance than “employee-only,” and a tax savings row that moves in lockstep when you change only the tax rate.
Employee-only path
Same $250/mo and return math, no employer deposits—lower ending balance.
Match-inclusive path
Extra principal each month (here +$50) compounds on the same monthly r.
Tax line + total benefit
Tax savings use only employee totals; “total potential benefit” adds that line to the portfolio value.
Limits of this model
- No fees, spreads, cash drag, or changing fund mixes—returns are one smooth monthly rate end to end.
- Match is a flat percent of your typed employee amount every month; no true-up, no per-pay-period caps, no vesting forfeiture.
- Tax savings ignore whether your plan is actually pre-tax, Roth, ISA-like, or taxable—confirm the wrapper with your payroll or tax preparer.
- Vesting schedules, holding-period rules, company blackout windows, and forced sale windows are not modeled.
- Horizon is capped at 80 years in code; extremely long horizons are unlikely to match any real plan document.
- All figures are educational projections for this website only—not a statement from your employer, broker, or tax authority.