A worked example

Thirty days on the 83(b)

Dev, 33, is incorporating and taking 2,000,000 founder shares at $0.001 on a four-year vest with a one-year cliff, in a company they expect to climb about 5x a year toward a Series A.

“Does filing the 83(b) actually matter, and what if the company doesn't take off?”

What the projection shows

Both directions, because the election isn't the one-way door the folklore makes it sound like. If she files, the whole grant is taxed once at a spread of almost zero. If she doesn't, every vesting tranche is ordinary income at whatever the stock is worth that year, which means tax on paper gains she can't sell. But if the price stays flat, the election has just bunched the same income into a single year, and not filing wins.