The full guide
Not tax advice. This page summarizes IRS instructions and Coinbase’s own help pages as of September 30, 2026. Coinbase may change its process before forms go out. Check with a tax professional for your situation.
Short version: Coinbase reported gross proceeds only for tax year 2025. For tax year 2026 it reports proceeds and cost basis, but only knows the basis of crypto you bought on Coinbase after 2025. Anything you moved in from another exchange or wallet is “noncovered”, and its basis shows blank (Coinbase calls it “Unknown”) unless you added the purchase details in Coinbase before the form was made.
What Coinbase sends you
| Form | What it covers | Source |
|---|---|---|
| 1099-DA | Sales, conversions and other disposals of crypto | Coinbase: Tax forms, explained |
| 1099-MISC | Crypto income of more than $600 (tax year 2025), reported as miscellaneous income | Coinbase: Tax forms, explained |
| Gain/loss report (not an IRS form) | “Every transaction you made on Coinbase that resulted in a capital gain or loss” | Coinbase: Tax forms, explained |
2025 vs 2026 on Coinbase
| Tax year | What Coinbase reports | What that means for you |
|---|---|---|
| 2025 | “Gross proceeds only” | You supplied basis for every sale yourself |
| 2026 | “Both gross proceeds and cost basis” | Basis is filled in for covered crypto: bought on Coinbase after 2025 and never moved out and back |
Source: Coinbase. The IRS rule behind it: a digital asset is “covered” only if it was acquired after 2025 in an account where the broker provided custody. Anything transferred in, or bought before 2026, is noncovered (IRS, Instructions for Form 1099-DA (2026)).
Why your Coinbase basis may be blank
- You transferred the coins in. When crypto is sold on Coinbase but was bought elsewhere, “Coinbase won’t have information about your purchase details” (Coinbase). For those sales the cost basis section is blank and the noncovered box (box 9) is checked, unless you gave Coinbase the details in time (Coinbase Help: Edit transaction details).
- You bought before 2026. Pre-2026 purchases are noncovered even if they never left Coinbase. Brokers may report their basis voluntarily but don’t have to (IRS i1099da).
- Stablecoin sales under $10,000. Brokers can use an optional method that leaves qualifying stablecoin sales off the form if your total for the year is $10,000 or less (IRS i1099da). They’re still reportable by you.
Coinbase itself says: “Many of you may see a missing cost basis because you transferred assets to Coinbase from other wallets or exchanges,” and that this shows up as “Unknown” or missing (Coinbase blog, Feb 10, 2026).
How to add missing basis inside Coinbase
Coinbase’s steps (Coinbase Help):
- Go to the Add transaction details page.
- In the Needs review tab, select the transaction.
- Select Add details. If one deposit came from several purchases, choose Split this transfer and add as many lots as needed.
- Enter the date acquired (purchase date) and the total cost basis (purchase price), then select Save.
Coinbase says it “will report cost basis on the recipient copy of the Form 1099-DA where cost basis information has been timely provided to Coinbase.” Coinbase’s help page does not state a cutoff date. If you add details, the form may mark the lot as customer-provided (box 8 on the 1099-DA is “broker relied on customer-provided acquisition information”, IRS i1099da). Either way, your return must use the basis your records support.
Coinbase also lets you pick FIFO, LIFO or HIFO in its tax center settings (Coinbase). Under IRS rules, if no identification is made the broker reports the earliest units first (FIFO), per account (IRS i1099da). For 2025 and 2026 you may identify units, or set a standing order, in your own books and records (IRS Notice 2026-20). The IRS notes this relief doesn’t change what brokers report, so your numbers and the form can differ.
Getting your Coinbase transaction history
Sign in, go to Taxes, select View Documents, and generate the gain/loss report under Custom Reports. The same area has a raw transaction report (Coinbase). The transaction CSV’s columns in the current version are: ID, Timestamp, Transaction Type, Asset, Quantity Transacted, Price Currency, Price at Transaction, Subtotal, Total (inclusive of fees and/or spread), Fees and/or Spread, Notes (column names as tracked by the open-source BittyTax Coinbase parser; older exports say “Spot Price at Transaction”). The rows that matter for basis are Receive and Deposit (coins coming in) and Send (coins going out). Every Receive without a matching Send from another account you own is a blank-basis risk.
Export the full history, from your first-ever transaction, from every exchange you’ve used. Your basis for a Coinbase sale may sit in a Kraken or Gemini file.
Reconciling Coinbase’s 1099-DA to Form 8949
Form 8949 has digital-asset boxes. Use the box the 1099-DA points to (IRS, Instructions for Form 8949):
| Your 1099-DA row | Held 1 year or less | Held more than 1 year | Column (e), basis |
|---|---|---|---|
| Basis reported to the IRS (box 2 checked) | G | J | The basis shown. Corrections go in (g) with code B |
| Basis blank or not reported (usually box 9 checked) | H | K | Your correct basis |
| No 1099-DA for the sale | I | L | Your correct basis |
Column (d) is always the proceeds shown on the form, which are already net of Coinbase’s fees (IRS i1099da, box 1f). Fees not reflected on the form go in (g) with code E (IRS i8949). If the 1099-DA row shows code Y, the broker couldn’t tell whether it’s short- or long-term: you decide from your own purchase date (IRS i1099da).
Worked example (illustrative numbers)
- Nov 10, 2025: buy 1.0 ETH on Kraken for $3,200 plus a $5.12 fee. Basis: $3,205.12.
- Feb 10, 2026: withdraw 1.0 ETH from Kraken (network fee 0.0035 ETH); 0.9965 ETH arrives on Coinbase 14 minutes later.
- Aug 1, 2026: sell 0.9965 ETH on Coinbase. Proceeds after fees: $3,487.75.
On Coinbase’s 1099-DA this sale is noncovered (transferred in), so basis is likely blank unless you added it. Held Nov 10, 2025 to Aug 1, 2026: short-term, box H. Column (d) $3,487.75, column (e) $3,205.12, gain $282.63. Without the Kraken record you’d have no basis to enter, and the whole $3,487.75 could look like profit.
One judgment call in this example: we added the 0.0035 ETH network fee’s basis to the coins that arrived rather than treating it as a sale. We didn’t find IRS instructions on transfer fees between your own accounts in the sources above; if the amounts matter to you, ask a tax professional.
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Sources (checked 2026-09-30; IRS and Coinbase help pages re-checked 2026-10-01)
- IRS, Instructions for Form 1099-DA (2026), revised Apr 30, 2026: https://www.irs.gov/instructions/i1099da
- IRS, Instructions for Form 8949 (2025): https://www.irs.gov/instructions/i8949
- IRS, Notice 2026-20: https://www.irs.gov/pub/irs-drop/n-26-20.pdf
- Coinbase Learn, “Tax forms, explained”: https://www.coinbase.com/learn/your-crypto/tax-documents-explained
- Coinbase Help, “Edit transaction details”: https://help.coinbase.com/en/coinbase/taxes/tools/edit-transaction
- Coinbase blog, “Coinbase and CoinTracker simplify crypto taxes ahead of the new Form 1099-DA” (Feb 10, 2026): https://www.coinbase.com/blog/coinbase-and-cointracker-simplify-crypto-taxes-ahead-of-the-new-form-1099-da
- BittyTax Coinbase parser (CSV column names; commit of Sep 15, 2026): https://github.com/BittyTax/BittyTax/blob/master/src/bittytax/conv/parsers/coinbase.py
- Koinly pricing: https://koinly.io/pricing/