Form 1099-DA field reference
Form 1099-DA Box 1g: Cost or other basis
What to check
- Include acquisition costs where allowed
- Reconcile transfers between brokers
- Keep lot-level documentation
Where Box 1g flows on your return
Box 1g's amount goes into the "Cost or other basis" column on Form 8949 alongside Box 1f's proceeds; the difference between the two, after any adjustment codes, is the gain or loss that carries to Schedule D.
How Box 1g works
Box 1g reports the broker's calculation of your adjusted basis in the digital asset sold, but only when the broker is required or chooses to report it. For a covered security this is generally mandatory; for a noncovered security where Box 9 is checked, the broker can choose to leave Box 1g blank entirely.
A blank Box 1g does not mean your basis is zero — entering zero is only correct when your actual cost basis was genuinely zero (for example, a token received for free with no taxable acquisition event already recognized). When the box is blank, you must determine basis yourself from your own purchase records, including transaction fees paid on acquisition, which are generally added to basis rather than deducted as a separate expense.
Basis reconciliation gets complicated for assets transferred between wallets or brokers, because the receiving broker often has no visibility into what you originally paid — see the transferred-in boxes (12a-12b) for how that basis gap can surface. Aggregate reporting for qualifying stablecoins or specified NFTs also leaves Box 1g blank by design, since those optional methods do not require basis reporting at all.
Worked example
Noah bought 3 units of a token for $600 total, including a small exchange fee added to basis, giving him a $600 cost basis. When he sells all 3 units, Box 1g correctly shows $600, and combined with Box 1f's $750 in proceeds, Form 8949 reports a $150 gain.
Continue the filing flow
Frequently asked questions
What if Box 1g is blank on my 1099-DA?
A blank Box 1g typically means the broker either was not required to report basis (a noncovered security with Box 9 checked) or used an optional aggregate reporting method that does not include basis. You need to determine your own basis from purchase records before reporting the sale on Form 8949.
Should acquisition fees be included in Box 1g?
Yes, transaction fees, commissions, and similar costs paid when you originally acquired the digital asset are generally added to your cost basis rather than treated as a separate deduction, so a correctly reported Box 1g should already reflect them.
Is a zero in Box 1g the same as a blank Box 1g?
No. A zero specifically means the broker determined your actual cost basis was zero, while a blank box means the broker did not report a basis figure at all — do not treat the two the same way when preparing Form 8949.