Crypto Tax Prep: What Records You Actually Need

Most crypto holders find out what records they were supposed to keep only after they need them — usually in February or March, staring at a tax deadline and an exchange account that only shows the last twelve months of activity. The IRS doesn't send a reminder, and exchanges aren't required to keep your full history available forever. This guide walks through exactly what documentation you need, why each piece matters, and how the rules have shifted now that exchanges are reporting more to the IRS directly.

The Baseline: Every Transaction, With Four Data Points

For every crypto transaction you've ever made — buying, selling, trading one asset for another, spending crypto on a purchase, or moving it between wallets — you need four things: the date, the amount and asset involved, the fair market value in US dollars at the time, and any fees paid. That applies whether the transaction happened on a centralized exchange, a decentralized protocol, or peer to peer. The IRS treats crypto as property, not currency, so nearly every disposal (selling, trading, or spending it) is a taxable event that has to be reported with a calculated gain or loss, and that calculation is only as good as the underlying data.

The fair market value piece trips people up the most, especially for trades between two crypto assets rather than a crypto-to-dollar sale. If you swapped ETH for SOL on a decentralized exchange, that's still a taxable disposal of your ETH, and you need the USD value of both assets at the moment of the trade — not just the exchange rate between them — to calculate the gain or loss correctly.

Cost Basis Records, Specifically

Cost basis is what you paid for an asset, including fees, and it's the number that determines how much of a sale is actually a gain. Without it, you don't have a partial problem — you have no defensible number at all. If you can't document what you paid, the IRS can treat your basis as zero, which means the entire sale proceeds get taxed as gain, even if you actually lost money on the position.

As of January 1, 2025, cost basis also has to be tracked separately for each wallet and account rather than pooled across everything you own, under IRS guidance in Revenue Procedure 2024-28. That means your records need to show not just what you paid for an asset, but which wallet or exchange account it was sitting in when you acquired it and when you disposed of it. If you moved assets between your own wallets along the way, you need a record connecting the withdrawal on one side to the deposit on the other, so the original basis carries forward instead of getting lost or duplicated.

What Changes With Form 1099-DA

Exchanges are now required to report more of this directly to the IRS, but the rollout is staged and it doesn't remove your recordkeeping burden. For 2025 transactions, covered brokers — most centralized US exchanges — report gross proceeds on Form 1099-DA, but not cost basis. That means you still have to supply your own basis figures to calculate the actual gain or loss on Form 8949. Basis reporting by brokers is expected to start applying to some transactions from 2026 onward, but only for assets acquired directly on that broker's platform after the rule took effect — anything you transferred in from elsewhere, or held before then, is still on you to document.

It's also worth being clear that receiving (or not receiving) a 1099-DA doesn't change what you owe. You're required to report all crypto income, gains, and losses regardless of whether an exchange sent you a form, and if a 1099-DA shows gross proceeds without basis, an unexplained gap between that number and what you report is exactly the kind of thing that invites a closer look.

Income Events, Not Just Disposals

Buying and selling isn't the only thing that needs documentation. Staking rewards, mining income, airdrops, and interest paid in crypto are generally taxed as ordinary income at the fair market value on the day you received them, and that value also becomes your cost basis for whatever you eventually do with those coins. It's easy to lose track of these because they often show up in small, frequent amounts rather than one clear transaction, but the IRS treats each one as a separate taxable event with its own date and value. If you've been staking or earning rewards for a few years without logging them, that's usually the biggest gap when people finally sit down to reconstruct their history.

How Long to Keep Everything

The IRS generally has three years from filing to audit a return, extended to six years if it suspects a substantial understatement of income — but crypto complicates the usual advice to just keep records for that window. Because cost basis carries forward for as long as you hold an asset, you effectively need to keep the acquisition records for anything you still own until you eventually sell it, plus the standard several years afterward. A coin you bought in 2018 and still hold today still needs its original purchase record preserved, even though the statute of limitations on that 2018 return has long since passed, because the sale — whenever it happens — will need to trace back to that original cost.

Where Crypto Transaction Log Fits In

This is the exact gap Crypto Transaction Log is built to close. Instead of hoping you remember to screenshot every staking reward or manually log every trade, you import your CSV or XLSX exports from each exchange and wallet, and it builds a single running history with dates, USD values, fees, and cost basis carried forward correctly — including through transfers between your own accounts. When it's time to file, you're working from one consolidated record instead of reconstructing years of activity from memory and partial exchange exports.

It won't file your return for you, and it's not a substitute for a tax professional if your situation is complicated. What it does is make sure the underlying data — the part every accountant, tax software product, and IRS notice ultimately comes back to — is actually complete and correct. It's free for unlimited transactions, so there's no reason to keep piecing this together in a spreadsheet by hand.

The Bottom Line

Good crypto tax prep isn't about a clever strategy — it's about having complete, dated, USD-denominated records for every acquisition, disposal, and income event, kept for as long as you hold the asset. Exchanges reporting more to the IRS through Form 1099-DA shifts some of that burden, but not all of it, and definitely not the parts involving transfers, self-custody wallets, or assets you held before the new reporting rules applied. Build the habit of capturing the four data points — date, amount, USD value, fees — as transactions happen, rather than reconstructing them under deadline pressure.