If you hold or trade stablecoins like USDC or USDT, you may have questions about how they're treated for tax purposes and why your cost basis may show as Unknown on Coinbase. This article explains how stablecoins are classified, why cost basis matters, and how you can update your records.
Important
Coinbase doesn't provide tax advice. Information here is provided to help customers understand their taxes, but should be reviewed before a customer uses it to file their taxes. To ensure this information works for you, please work with a professional.
Stablecoins and taxes
From a U.S. tax perspective, fiat-backed stablecoins are generally treated like all other digital assets — as property, not cash.
Even though USDC or USDT is designed to track the dollar, the IRS views them similarly to ETH or BTC. This means:
Cost basis matters: Every stablecoin unit has a cost basis — what you paid when you acquired it.
No automatic $1 assumption: Platforms cannot simply assume your cost basis is exactly $1.00. Fees, market fluctuations, or how you earned the coin (e.g., as a reward) can change that value.
Taxable stablecoin activity
The following types of stablecoin activity may have tax implications:
Swapping other crypto into a stablecoin: Swapping ETH into USDC, for example, is generally treated as a disposition of ETH for its fair market value at the time, with a gain or loss relative to your ETH cost basis.
Spending stablecoins: Paying a merchant in USDC can be treated as disposing of stablecoin property in exchange for goods or services, potentially triggering a gain or loss if the value has changed relative to your basis.
Earning income in stablecoins: Staking rewards, yield, card rewards, referral bonuses, and other promotional programs paid out in stablecoins are typically treated as income at the time you receive them, valued in fiat terms. Those amounts included in your income then become your cost basis in the stablecoins going forward.
Swapping between stablecoins: Moving from one stablecoin to another (e.g., USDT → USDC) can be treated as disposing of one property and acquiring another, even if the nominal dollar value appears unchanged.
Important
Simply holding a stablecoin in the same account, or transferring a stablecoin between wallets you control without any sale, swap, or income component. However, those movements can still matter for record-keeping.
Stablecoin cost basis assumptions
Even though USDC is designed to be worth $1, Coinbase can't just treat its cost basis as $1 for every unit. Because USDC is treated as property rather than cash under current U.S. guidance, assuming a $1 basis for every unit would be an oversimplification that is not supported by the rules.
There are a few reasons:
Acquisition method: Did you buy it at $1.00? Or was it a reward valued at $1.01 at the time of receipt?
Market variance: In volatile moments, stablecoins can trade slightly above or below $1.00.
The off-platform gap: If you buy USDC elsewhere and transfer it to Coinbase, we don't know what you originally paid for it. Without that data, we can't accurately report your gains or losses.
Stablecoin $1 cost basis toggle
To make it easier for you to manage stablecoin cost basis, Coinbase offers an optional toggle in your Tax Center settings that lets you apply a default $1 cost basis to USDC transfers.
Important
This toggle is entirely optional. Enabling it means you are choosing to assign a $1 cost basis to transferred-in qualifying stablecoins at your own discretion. Coinbase is not making this assumption on your behalf. You are responsible for ensuring this reflects your actual acquisition cost.
To enable the stablecoin cost basis toggle:
Go to your Tax Center.
Select the Settings tab.
Find the Stablecoin cost basis section.
Toggle on Apply $1 default cost basis for stablecoin transfers.
Review the confirmation message and select Confirm.
This applies a $1.00 per-unit cost basis to qualifying stablecoin transfers (e.g., USDC) that were received from external wallets and currently have unknown cost basis and updates your gain/loss calculations in the Tax Center to reflect the $1 basis.
The updated cost basis will not appear on your recipient copy of Form 1099-DA for your reference when filing taxes. For customers eligible for designated stablecoin aggregation over $10,000, only the number of units, number of transactions, and proceeds will be reported on the 1099‑DA.
The cost basis toggle does not:
Apply to stablecoins other than USDC or non-stablecoin assets
Override a cost basis value you have entered manually
Change what Coinbase reports to the IRS for the tax year
Example
You transferred 500 USDC from an external wallet to Coinbase. The cost basis shows as Unknown because Coinbase doesn't have your original purchase records. By enabling the stablecoin toggle, a $1.00 per-unit cost basis ($500 total) is applied to this transfer. If you later sell or swap that USDC, your gain/loss will be calculated using the $1 basis.
Stablecoin reporting on Form 1099-DA
The IRS introduced an optional reporting method for qualifying stablecoins. Here is how it may appear on your Form 1099-DA:
The $10,000 threshold: If your total sales of a qualifying stablecoin are $10,000 or less for the year, Coinbase is generally not required to report those specific sales on Form 1099-DA.
Aggregate reporting: If you exceed $10,000 in sales, Coinbase won't list every individual micro-transaction. Instead, you'll see a single lump sum for that specific stablecoin.
Your responsibility: Even if your transactions are under $10,000 and don't appear on a 1099-DA, you are still required to report any taxable gains or losses on your personal return.