For NFTs received as income (airdrops, creator royalties paid in NFTs, giveaway wins), the floor price on the day you received them is your cost basis.

If you don’t record that price on day one, you’ll struggle to prove it months or years later when you sell.

Why Mint Day Price Matters

You won an NFT giveaway on Twitter. The collection’s floor price was 0.8 ETH ($1,200) the day it hit your wallet.

Tax treatment:

  • You received $1,200 in income (taxable immediately)
  • Your cost basis in the NFT is $1,200

Six months later, you sell it for 1.2 ETH ($1,800).

  • Proceeds: $1,800
  • Basis: $1,200
  • Capital gain: $600

If you forgot to record the $1,200 floor price and can’t prove it, the IRS might assume $0 basis—making your entire $1,800 proceeds a taxable gain.

When This Applies

Airdrops: You received a free NFT from a protocol. Floor price on airdrop date = your basis.

Creator royalties paid as NFTs: A marketplace paid you a royalty in the form of an NFT. FMV on receipt = income and basis.

Gaming rewards: You earned an NFT as a prize. FMV on day earned = income and basis.

Giveaway/raffle wins: You won an NFT in a contest. FMV on day won = income and basis.

This does NOT apply to NFTs you bought (your basis is what you paid).

How to Record Floor Price

On the day you receive the NFT:

  1. Check OpenSea, Blur, or LooksRare for current floor price
  2. Screenshot the floor listing with timestamp
  3. Record the ETH price in USD at that moment
  4. Save the screenshot with the NFT’s token ID and date

Example documentation:

  • Date: March 15, 2024
  • NFT: Cool Cats #4521
  • Floor price: 0.6 ETH
  • ETH/USD: $1,850
  • Basis: $1,110
  • Screenshot: saved to Google Drive

Three minutes of work saves you from audit issues years later.

If the Collection Has No Floor Yet

For brand-new mints with no trading history, estimate fair market value using:

  • Mint price: If it was a paid mint, similar NFTs likely trade near mint price initially
  • Comparable collections: Similar art/utility NFTs in the market
  • First sales data: Check the first few sales on marketplaces within 24 hours

If there’s genuinely no market (brand new, zero liquidity), you can argue $0 FMV at receipt. But document why you concluded that.

Example: Free Mint That Mooned

You minted Goblintown for free (plus 0.05 ETH gas). Floor went to 4 ETH within days.

Day 1 (mint day):

  • Mint price: Free
  • Gas: $75
  • Floor: Not established yet
  • Basis: $75 (just the gas)

Day 3 (floor established at 4 ETH = $6,000):

  • If you held from Day 1, your basis is still $75 (you didn’t receive it as income on Day 3)
  • If you sell on Day 10 for 3 ETH ($4,500), your gain is $4,425 ($4,500 - $75)

But if you received it as an airdrop on Day 3 when floor was 4 ETH, your basis would be $6,000 (taxable as income immediately), and selling for $4,500 creates a $1,500 loss.

Proving Basis Years Later

The IRS can audit you 3-6 years after you file. If you sold an NFT in 2024 and get audited in 2027, can you prove what the floor price was in 2024?

Without screenshots or saved data:

  • OpenSea might not have historical floor charts that granular
  • Wayback Machine archives are incomplete
  • Relying on memory won’t convince the IRS

With screenshots:

  • Show exact floor on exact date
  • Match token ID to wallet address
  • Prove basis with blockchain + market evidence

The IRS accepts reasonable documentation. A screenshot of OpenSea floor + Etherscan wallet receipt is strong proof.

Action Step

Review all NFTs you received as airdrops, rewards, or giveaways this year. For each one, look up the floor price on the day you received it.

If you can still find historical price data, record it now. If not, check Dune Analytics dashboards, NFT price trackers, or Discord announcement channels for clues about floor price history.

Create a “Received NFTs” spreadsheet:

  • NFT name/token ID
  • Date received
  • Floor price on that date (ETH)
  • ETH/USD rate
  • Basis in USD
  • Screenshot/proof saved where?

Going forward, set a calendar reminder: every time you receive an NFT as income, spend 3 minutes documenting the floor price immediately.

Losing this data means you’ll either overpay taxes (assuming $0 basis) or face audit trouble. Recording it takes almost no time and protects you completely.