1099-DA Basis Gap Checker (2026 crypto) by ReadyStack

See which of your 2026 crypto sales reach the IRS with box 1e blank - and price what that blank costs.


Click Add to Firefox on this page. Nothing to unzip, no developer mode - the free version runs right away.

• Covered / noncovered test — Decides, for one lot, whether the broker prints your cost basis or leaves box 1e blank - a digital asset is covered only if it was acquired at that same broker on or after Jan 1, 2026 and held there until the sale.
• Phantom gain math — Shows the gap between your true gain and the gain the IRS matching system reads off the form when basis is blank, which is the full gross proceeds.
• Combined rate stack — Adds your federal rate (long-term band or ordinary rate), your state rate and the 3.8% net investment income tax into the single rate that lands on the phantom gain.
• Section 6662 penalty line — Adds the 20% accuracy-related penalty on top when you tick that you cannot substantiate the lot's acquisition date and cost from your own records.
• Lot worksheet export (full version) — Writes every lot you have checked to a CSV basis-substantiation worksheet you keep on disk and hand to your preparer.
• Deadline reminders (full version) — Sets browser alarms for the Dec 31 2026 close of the tax year and for the window when 1099-DA forms arrive, so a blank box 1e is not a February surprise.

| You type | |
|---|---|
| Where this lot came from | default Transferred in from another exchange or a self-custody wallet |
| Gross proceeds from the 2026 sale | default 42000 |
| Your documented cost basis for the lot | default 31500 |
| Holding period | default Long-term (held more than 1 year) |
| Long-term capital gains band | default 15 |
| Ordinary federal rate (used if short-term) | default 24 |
| State income tax rate | default 5 |
| Net investment income tax applies (3.8%) | default True |
| I can substantiate this lot's date and cost from my own records | default False |

| It answers | |
|---|---|
| What box 1e will say | |
| Your true gain | USD |
| Gain the IRS reads off the form | USD |
| Phantom gain | USD |
| Combined rate on the phantom gain | % |
| Tax on the phantom gain | USD |
| 20% accuracy-related penalty | USD |
| Total exposure on this one lot | USD |

Permissions requested: storage, alarms


Free: the calculation in the popup, no key, no limit. Full version ($60): download the result as .csv and deadline reminders - one licence key per person or team seat. Get it: https://buy.polar.sh/polar_cl_42QJWQ2aEv6O3mF1hF96fcvG5EW1DSBIYQsv33b37fv


When you use the tool, the extension sends one anonymous count a day (the tool’s name only — no inputs, no personal data). Turn it off on the first page after install. Firefox asks first and sends nothing unless you allow it. A licence key is checked with the payment provider (Polar) only when you enter one.