The EIS & SEIS calculator that shows the downside too.
Most calculators show the relief. This one also shows your true net downside per pound if the company fails, what a successful exit keeps out of capital gains tax, and the two dates every investor forgets: how long you must hold, and when your claim window closes. Every rule is linked to the official record below.
A gain from selling other assets that funds this investment — its CGT is deferred while you hold.
Assumes you have sufficient income tax liability to absorb the relief, the company keeps its EIS status for 3 years, and loss relief is claimed against income at your stated marginal rate. CGT figures use current rates for shares (18% basic, 24% higher and additional). Information, not tax or investment advice — confirm your position with a qualified adviser.
Every relief, in one place
EIS and SEIS are not one tax benefit but a stack of six. The calculator above computes the first five; the sixth depends on your estate, so we state the rule rather than guess your number.
EIS 30% · SEIS 50% of the amount subscribed, against this year's income tax or carried back one year.
If the company fails, the net loss (after income tax relief) is deductible against income at your marginal rate — up to 45%.
No capital gains tax on the growth when you sell after the 3-year holding period.
Tax on gains made up to 36 months before or 12 months after the investment is deferred while you hold — and can be re-deferred.
Half of a gain reinvested into SEIS shares is permanently exempt — the tax never returns, even if the company fails.
Unquoted EIS/SEIS shares usually qualify for Business Relief: 100% IHT relief after 2 years if still held at death. From 6 April 2026 the 100% rate applies up to the government's per-estate allowance for business and agricultural property (announced at £2.5m), with 50% relief above it.
Checked against the official records
Nothing here is invented: each figure the calculator produces is arithmetic on rules published by HMRC and GOV.UK. The sources, so you can verify every number yourself:
Rules as published at the time of writing; reliefs depend on your circumstances and on the company keeping its qualifying status. Tero is software. We are not a fund, we do not hold client money, and we do not provide investment, tax or legal advice. Information, not tax advice. Capital at risk.