Form 1099-DA field reference
Form 1099-DA Box 1c: Number of units
What to check
- Compare units with trade history
- Include fractional units
- Investigate aggregate statements
Where Box 1c flows on your return
Box 1c doesn't have its own Form 8949 line, but the unit count is part of describing the property sold on Form 8949 and is what you multiply against your own per-unit cost records when Box 1g needs to be reconstructed.
How Box 1c works
Box 1c reports the quantity of digital-asset units disposed of in the transaction, expressed to as many as 18 decimal places to accommodate the very small fractional amounts common in crypto trading — a level of precision far beyond what whole-share stock reporting normally needs.
When a broker uses the optional aggregate reporting method for qualifying stablecoins or specified NFTs, Box 1c can show the combined total units across every transaction folded into that single line rather than the amount from one discrete trade, so it won't always tie to a single entry in your own trade log.
Fractional-unit trading, staking-reward accruals, and airdrops complicate reconciliation because each add-on can create its own tiny tax lot with its own acquisition date. Compare Box 1c closely against your platform's trade history, especially around any transaction involving partial-unit rounding, to confirm the broker's total matches what you actually disposed of.
Worked example
Jordan sells 2.153847691 units of a token in one transaction. Box 1c on the resulting 1099-DA shows exactly "2.153847691," matching the fractional-unit precision from Jordan's exchange trade confirmation, so no rounding discrepancy needs to be investigated.
Continue the filing flow
Frequently asked questions
Why does Box 1c show so many decimal places?
Digital assets are commonly traded in very small fractional amounts, so the IRS allows brokers to report unit counts to up to 18 decimal places — far more precision than whole-share stock reporting typically requires.
Does Box 1c ever combine multiple trades into one number?
Yes, when the broker uses the optional aggregate reporting method for qualifying stablecoins or specified NFTs, Box 1c can show the total units across all the combined transactions rather than a single trade's quantity.
What should I do if Box 1c doesn't match my own trade records?
Compare it against your exchange or wallet trade history transaction by transaction, paying attention to fractional-unit rounding, staking rewards, and airdrops, which can each create separate small lots that are easy to double-count or miss.