First check whether the October deadline applies to you
The IRS says many individual filers who requested a valid extension for their 2025 federal return must file by October 15, 2026. That is an extension of filing time, not additional time to pay: estimated taxes were ordinarily due with the April deadline. Special circumstances, disaster extensions, international taxpayers and business-return rules may differ. Do not assume this is every crypto holder's deadline. This checklist covers preparing accurate records for an applicable U.S. return, not deciding whether you personally owe tax.
Why Form 1099-DA does not replace your records
Brokers may report proceeds from 2025 digital-asset transactions on the new Form 1099-DA. The IRS warns that most statements for 2025 transactions do not include cost basis. That means the form may show disposal proceeds while leaving acquisition cost, acquisition date and earlier wallet transfers for the taxpayer to substantiate. A number printed by a broker is useful evidence but not a complete inventory of everything you have ever done with the asset.
Gather source history before exporting a tax report
| Record | Question to resolve |
|---|---|
| Exchange history | Have you imported all accounts and all relevant years? |
| Self-custody addresses | Were incoming and outgoing transfers captured? |
| Internal transfers | Does the tax tool link the sending and receiving side correctly? |
| Rewards and income | Are staking, mining and other receipts recorded and classified? |
| Trading fees | Are fees recorded consistently with the software's supported treatment? |
| Missing cost basis | Is each warning explained by evidence, rather than ignored? |
| Broker forms | Do reported disposals reconcile with your transaction ledger? |
This is a *data-integrity checklist*, not a list of taxable events. The correct tax treatment of a transaction depends on its facts and current rules.
Resolve missing basis instead of accepting a plausible total
CoinLedger documents recurring reasons for missing-basis warnings: absent historical exchanges, duplicate imports, uncategorized onchain interactions and transactions from a wallet not yet included. These are upstream data issues. If the total capital gain looks plausible but a warning remains unexplained, the report can still be materially wrong. Investigate the specific asset and transaction, gather the original purchase or receipt record, and review how the software classifies transfers before treating a warning as resolved.
CSV and API imports need different safeguards
Koinly's exchange import guidance describes API-based synchronization and CSV imports as alternative ways to collect transaction history. API data may update repeatedly; a CSV requires exporting and importing later activity again. In either route, verify the date range, transaction types, duplicate handling and wallet identity. A successful import message is not proof that the platform supplied every trade, transfer, reward or fee. Keep the original exports and a record of the filters used.
A final pre-filing review
- Match opening and closing balances by asset and account.
- Review all material missing-basis warnings and unexplained adjustments.
- Pair genuine transfers between addresses under your control before interpreting disposals.
- Compare Form 1099-DA proceeds against the underlying transactions, noting missing basis.
- Check classification of staking, rewards, swaps and fees against official tax guidance.
- Retain unedited source files and a dated copy of the software settings and report.
- Resolve uncertainties with a qualified U.S. tax professional before filing rather than guessing.
Changing a transaction type to make an error icon disappear is not an evidence-based reconciliation.
After the deadline
A dated checklist remains useful for later amendments or ongoing record hygiene, but deadlines and broker reporting requirements evolve. Preserve this article's October 2026 context; do not read its filing date as a recurring annual rule. The Jepeta Koinly workflow guide covers one product's documentation, while this guide focuses on the underlying records independent of vendor choice. This article is U.S.-specific educational content, not individual tax advice.
Evidence and source-review method
- structured comparison — Primary-source editorial comparison of documented security or import/tax procedures, including a task-oriented checklist and limits. No live wallet test, tax filing, or exchange API account verification is claimed. · evidence · observed Oct 9, 2026
Editorial transparency
This article was prepared with AI-assisted tools and an evidence-oriented source review. Citations and limitations are provided below. Documentation comparison is not a hands-on test; historical content is not automatically certified under the later independent editorial review process. Editorial standards and corrections.
Sources
- IRS: request an extension, October 15, 2026 · primary · verified Oct 9, 2026 · published Apr 14, 2026
- IRS: reminders for taxpayers about digital assets and Form 1099-DA · primary · verified Oct 9, 2026 · published Jan 28, 2026
- CoinLedger: common causes of missing cost basis warnings · primary · verified Oct 9, 2026
- Koinly: exchange and service import methods · primary · verified Oct 9, 2026 · published Jun 24, 2026