You have worked at a private company for six years. In a private market marketplace, you may accumulate multiple forms of equity over time — ISOs from 2019, NSOs from 2021, and RSUs that vested in 2023. A secondary buyer has expressed interest in purchasing a portion of your position. The offer looks clean. But before you sign anything, one question deserves focused attention: which shares are you actually selling? If you're still building foundational context on how pre-IPO investing structures, taxation, and liquidity interact in secondary transactions, review the complete guide to pre-IPO investing before selecting specific tax lots.

This is not a paperwork formality. Tax lot selection — identifying precisely which tranche of equity you are disposing of — can be the difference between long-term capital gains treatment and ordinary income, between a gain that qualifies for QSBS exclusion under Section 1202 and one that does not, or between a tax bill that is manageable and one that surprises you in April.

What follows is a plain-language framework. It is not tax advice, and the right answer for your situation depends on facts a qualified tax advisor must review. But understanding the mechanics allows you to ask the right questions and avoid the most common structural mistakes.

Why pre-IPO sellers have multiple lots in the first place

Private company equity accumulates in layers. A founding engineer might receive an initial ISO grant in year one, a refresher grant in year three, additional NSOs tied to a promotion in year four, and RSUs after the company adopted a new equity plan. Each of these is a separate tax lot with its own cost basis, ordinary income recognition history, and holding period clock.

  • Incentive Stock Options (ISOs): exercised at a strike price; no ordinary income at exercise for regular tax purposes, but spread at exercise is an AMT preference item. Holding period for long-term capital gains begins at exercise date.
  • Non-Qualified Stock Options (NSOs): spread between strike and fair market value (typically set by 409A valuation) is ordinary income at exercise. Holding period for capital gains begins at exercise date.
  • Restricted Stock Units (RSUs): full fair market value at vesting is ordinary income. Cost basis equals that income-inclusion amount. Holding period begins at vest date.
  • Restricted Stock Awards (RSAs): if an 83(b) election was timely filed, basis equals the purchase price at grant and the holding period begins then. If no 83(b) was filed, basis equals fair market value at each vesting date.

When you sell on the secondary market, the buyer's counsel or the platform's transfer agent will ask you to identify the specific shares being transferred. If you do not specify, the default for most brokerages and transfer agents is FIFO — first in, first out. FIFO is simple, but it is not always optimal.

The four dimensions of lot selection

1. Holding period

Shares held more than one year qualify for long-term capital gains rates — currently 15% or 20% at the federal level depending on income, plus the 3.8% Net Investment Income Tax for higher earners. Shares held one year or less are taxed as short-term capital gains, which are taxed at ordinary income rates. The difference between a 20% rate and a 37% rate on the same dollar of gain is substantial. All else equal, selling your oldest, longest-held lot first reduces your effective rate.

2. Cost basis

Higher basis means less gain recognized on the same sale price. If you exercised ISOs in 2019 at a $2.00 strike when the 409A was $2.50, and RSUs vested in 2023 when the 409A was $18.00, the RSU shares carry a far higher basis. Selling RSU shares into a secondary market at $22.00 produces a modest gain; selling the 2019 ISO shares at $22.00 produces a gain that is eighteen times larger per share.

3. QSBS qualification

Section 1202 of the Internal Revenue Code can exclude up to $10 million — or 10 times your basis, whichever is greater — in gain from federal tax entirely, provided the stock is Qualified Small Business Stock (QSBS). The qualifying conditions include: the stock must be original-issue stock acquired at original issuance (not on the secondary market), from a domestic C-corporation with gross assets under $50 million at time of issuance, and held for more than five years. If some of your lots qualify and others do not, the specific lot you designate for a secondary sale directly determines whether this exclusion is available.

QSBS exclusion is one of the most valuable benefits in the U.S. tax code for startup equity holders — and it is lot-specific. Selling the wrong tranche can forfeit the exclusion entirely.

4. Prior AMT exposure

If you exercised ISOs in a prior year and paid Alternative Minimum Tax (AMT) on the spread, you may have an AMT credit carryforward. When you sell those ISO shares in a regular tax year where your regular tax liability exceeds your AMT liability, that credit becomes usable. Selling the ISO lot that triggered prior AMT can therefore produce a tax benefit in the year of sale — a factor that changes the calculus on which lot is most efficient to dispose of first.

Practical mechanics: how to specify a lot in a secondary transfer

Secondary transfers of private company shares typically involve a stock transfer agreement, an assignment of membership interest (if held through an SPV), or a board-approval process initiated by the company's transfer agent. In each case, the seller designates the specific certificate numbers, grant agreement references, or equity plan grant IDs corresponding to the shares being sold.

Most equity plan platforms — Carta, Pulley, and similar — allow you to view your outstanding grants and their associated details, including grant date, exercise date, vesting schedule, and current certificate status. Before executing a secondary sale, pull this data and share it with your tax advisor so lot selection is a deliberate choice, not a default.

  1. Export your full equity summary from your company's cap table platform, including grant type, grant date, exercise date (if applicable), number of shares, and cost basis per share.
  2. Identify which lots are long-term (held over one year from exercise or vest), which qualify for QSBS treatment, and which carry prior AMT basis adjustments.
  3. Model the after-tax proceeds for each plausible lot selection scenario at the proposed secondary sale price.
  4. Confirm with a qualified tax advisor before signing any transfer documentation.
  5. Specify the chosen lot explicitly in the transfer agreement, referencing certificate numbers or grant IDs to avoid ambiguity.

Common mistakes sellers make

Accepting FIFO without reviewing the alternatives
FIFO is the default. It is not the optimal default for most multi-lot holders. Always compare.
Selling QSBS-qualifying stock before the five-year mark
If a qualifying lot is at four years and eight months, a brief delay before signing transfers the tax character of the entire gain.
Forgetting the 83(b) window on restricted stock
If you received an RSA and filed an 83(b), your holding period started at grant. If you did not file, it started at each vest date. The records from years ago determine your current lot structure.
Conflating the secondary sale date with the exercise date
The holding period clock for capital gains purposes starts at exercise (for options) or vest (for RSUs), not at the date of the secondary transfer. The secondary sale is simply the recognition event.
Not accounting for state taxes
Several states — including California — do not conform to the federal QSBS exclusion and tax the full gain at ordinary rates. Federal planning and state planning are separate exercises.

Before you sell

The secondary market for pre-IPO equity has matured significantly. Platforms can settle transfers in one to five business days. Legal documents are templated. ROFR processes run in parallel. What has not changed is that sellers who do their lot-selection homework before entering the process extract materially better after-tax outcomes than those who treat the tax decision as a post-close detail.

If you are evaluating a secondary sale and want to understand the full seller-side process — from pricing your shares to navigating ROFR to closing transfer documentation — our seller playbook walks through each stage in sequence.

When you are ready to list, visit the sell page to submit your position details. Limen Markets' team will match your specific grant information against active buyer demand and provide indicative pricing within one business day. For the complete reference on basis, holding periods, and reporting, see our tax and legal handbook.