a founder incorporates a delaware c-corp on a tuesday, issues 5m shares to herself at $0.0001 a share, signs a four-year vesting schedule. fifty dollars of stock, four-year cliff, standard. her lawyer sends a packet with a tab labeled "83b election — file within 30 days." she's busy. she puts it on a list.
four years later the company raises a series c at a $400m valuation. her vested shares are worth roughly $40m on paper. she gets a tax bill from the irs treating the spread between her $0.0001 strike and the fair market value at each prior vesting tranche as ordinary income — every year, all the way back to that tuesday. the total exceeds $1m in federal taxes. she pays it on shares she cannot sell, because she missed a 30-day window.
the 83(b) election is the lowest-cost, highest-leverage piece of tax paperwork in the founder kit. it costs $50 in postage and ten minutes. skipping it converts a single capital-gains event on exit into a series of ordinary-income tax bills at every vesting cliff, often hundreds of thousands of dollars before the company has produced any liquidity to pay them with. the window is statutory. the irs does not grant extensions.
what 83(b) actually does
when restricted stock is granted with vesting, the irs treats each tranche as taxable income the moment it vests — the spread between what you paid (the strike) and the fair market value at vesting (the 409a) is ordinary income that year. on a fast-growing startup the 409a goes up every round, so the spread compounds.
an 83(b) election is a one-page form filed with the irs that says — "tax me now, on the value at grant, not at each vesting cliff." at grant, the value is usually nominal. a founder issued 5m shares at $0.0001 has a $500 paper stock with a $500 strike. the spread is zero. tax owed under 83(b) is zero. file the election and the irs treats the entire grant as a single event at grant, with capital-gains treatment from there forward.
the 30 days are calendar days from the grant date, not business days. the form goes by certified mail with return receipt to the irs service center that processes returns for the taxpayer's home state. you keep the green postmark card forever. a copy goes to the company. a copy goes in the founder's personal tax file.
what the bill looks like when you skip it
run the arithmetic on a founder with 5m shares at a $0.0001 strike, four-year vesting. file 83(b) at incorporation — tax owed is $50, payable as long-term capital gains on eventual sale.
skip 83(b) and the math changes at every cliff. year one, 1.25m shares vest. the 409a has moved to $0.10 after a seed round. ordinary income — $125k. at a 37% federal rate, tax owed is $46k, in cash, the year the cliff hits.
year two, post series a. 409a is $0.80. 1.25m shares vest. ordinary income — $1m. tax owed — $370k.
year three, post series b. 409a is $2.40. ordinary income — $3m. tax owed — $1.1m.
total bill on illiquid stock over three years of vesting — roughly $1.5m. against an 83(b) cost of $50. the founder pays it from her w-2 salary, from savings, or by taking secondary in a way that triggers additional gain. the company cannot pay it for her without creating a separate tax problem.
the early-employee version is worse
founders can usually scrape together the cash. early employees can't. an engineer who joins at month six with 200k shares at a $0.05 strike, no 83(b), watches each cliff turn into a 5-figure tax bill against the w-2 salary they're already living on. some sell shares back to the company to cover it. some resign before the next cliff to stop the bleeding.
the company that didn't require the 83(b) at grant has just lost an engineer over a paperwork failure. the lawyer handling the cap table should require a postmarked 83(b) on every restricted stock grant before logging the issuance. companies that don't enforce this end up with surprise turnover at the 12-month cliff.
the cases where 83(b) is actually wrong
there is one. if the value at grant is materially above what the founder can pay, filing 83(b) creates an immediate cash tax bill the founder can't cover. this happens late — a founder receiving shares at year three of a company with a $50m 409a should not file without modeling the cash bill. for founders at incorporation, with a near-zero strike, the answer is always file. for an engineer joining at series b with a higher strike, run the math.
restricted stock units (rsus) are not eligible for 83(b). only restricted stock with a substantial risk of forfeiture qualifies. most startup grants below series b are restricted stock, not rsus.
how zift handles this
zift does not file 83(b) elections for you. it does track every equity grant on the cap table and flag the 30-day deadline as a calendar event the day the grant is issued. on monday morning the briefing names the grants in the prior week and the postmark deadlines coming up. when a deadline approaches without a 83(b) on file, the briefing escalates.
if you're a finance lead at a series a team running stock administration for the founding team and early employees, zift handles that too. the dashboard tracks 83(b) status per grant and surfaces the ones missing a postmark receipt before they go past the window.
the tax code gave founders a 30-day door and a one-page form. the founders who walk through the door pay $50. the ones who don't pay their salary back to the government for the privilege of holding their own stock.