vestingtax.com
Estimate vest tax

What is the supplemental stock plan lot detail report?

Supplemental lot detail reports often hold the vest price you need when 1099-B basis is wrong.

Rates and rules change. Check the tax year and last-reviewed date on each page, then confirm against IRS or state guidance before you file.

Spot an outdated rate or date?

We update when we can, but we miss things. Send a link to the official source if you have one.

Email us

Start here

Brokerages that administer equity plans often provide a supplemental report alongside the . It usually lists each lot's and price, the information the may leave blank. It is often the cleanest place to find the numbers you need to adjust basis.

Why this happens

The official may report $0 or missing basis for shares, especially noncovered lots.

Plan administrators know the details, so they include them in a separate supplemental statement.

That supplemental detail is for your records and return preparation; it is generally not filed with the IRS by you.

Matching each sold lot to its price is how you compute the correct basis adjustment.

What to check

  • Whether your broker provides a supplemental or 'stock plan' statement.
  • and per share for each lot.
  • How sold lots map to the lots listed.
  • That the supplemental basis matches your own confirmations.
  • Short-term vs long-term classification for each lot.

Common mistake

Filing from the alone and ignoring the supplemental report. The may not tell the whole story, the supplemental detail is often where the real basis lives.

Example scenario (hypothetical)

Illustration only, not your tax situation.

Example: Casey's shows $0 basis on a sale of 60 shares. The supplemental report shows those 60 shares vested at $48. Casey uses $48 per share ($2,880) as the adjusted basis when reporting the sale.

When to get help from a tax pro

  • The supplemental report and your own records disagree.
  • Lots were sold in pieces and basis tracking is unclear.
  • You cannot locate a supplemental statement and the shows $0 basis.
  • You have wash-sale concerns across lots.

Related calculators

Related pages

For learning, not filing

Grants, employers, and states all differ. Use your own documents and a qualified tax professional before you make decisions from this guide.