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When assets are deposited from an external source, Anchorage may not have the original acquisition details. If cost basis isn’t provided, the system defaults to $0, which may affect your reported gains/losses. This information ensures that tax lots and gains/loss calculations reflect accurate historical cost basis. Cost basis information you provide may impact data reported on 1099-DA, for eligible US tax-paying entities. Anchorage Digital partners with Taxbit to support tax reporting, including 1099-DA, 1099-MISC, and 1099-INT.
Anchorage Digital does not provide financial, tax, or legal advice. Consult a qualified professional for guidance specific to your situation.

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Cost basis method (HIFO)

Anchorage Digital uses HIFO (Highest-In, First-Out) by default for cost basis accounting unless otherwise configured. Example (HIFO):
PurchaseQuantityPrice
Purchase 110 BTC$20,000/BTC
Purchase 220 BTC$22,000/BTC
Purchase 315 BTC$35,000/BTC
If 25 BTC are sold, HIFO assumes:
  • 15 BTC from Purchase 3 sold first (highest cost)
  • Remaining 10 BTC from Purchase 2
Taxbit offers HIFO, LIFO, and FIFO. Contact Anchorage customer service to request a change in default cost basis methodology. Individual lot selection is not currently available.

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Default logic and validations

  • If a deposit is missing user-provided cost basis, the system assigns a default of 0. Provide cost basis promptly after deposits complete to avoid inaccurate reporting.
  • Cost basis updates support up to 100 lots per transaction.
  • The acquisition date must be on or before the transfer/deposit date.
  • Trades may have small rounding differences due to settlement precision. Your internal reconciliation should account for this.

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API workflow

1

List tax accounts

Identify tax accounts your API credentials can access.GET /tax/accounts
{
  "accounts": [
    {
      "taxAccountId": "acc_123",
      "name": "Example 123"
    }
  ]
}
2

List deposit transactions for a tax account

Retrieve deposit transactions for a given tax account. Filter by hasCostBasis=false to return only deposits missing user-provided cost basis.GET /tax/accounts/{taxAccountId}/transactions
{
  "data": [
    {
      "assetType": "BTC",
      "externalId": "9be748be-d760-4d36-90f8-86b699c4e8bd",
      "id": "9cd9f4d4-078b-4e44-a308-7662fec0f546",
      "receivedAssets": [
        {
          "acquisitionDatetime": "2026-04-06T17:55:48.083Z",
          "costBasis": "2500",
          "quantity": "1.0"
        }
      ],
      "transactionTime": "2022-07-30T22:15:31.99999Z"
    }
  ],
  "page": {
    "next": "<next page url>"
  }
}
3

Provide cost basis for a deposit transaction

Submit one or more lots whose total quantity matches the deposit quantity.PATCH /tax/accounts/{taxAccountId}/transactions/{transactionId}
{
  "lots": [
    {
      "quantity": "0.7500",
      "costBasis": "15000.00",
      "acquisitionDate": "2024-05-10T14:19:52.539Z"
    },
    {
      "quantity": "0.5000",
      "costBasis": "12000.00",
      "acquisitionDate": "2023-11-02T14:19:52.539Z"
    }
  ]
}
Validation rules:
  • Total lot quantities must equal the transaction quantity
  • Acquisition date must be on or before transfer date
  • Maximum 100 lots per transaction
4

Confirm the update

Re-fetch the transaction and verify costBasis is no longer 0 and lots were accepted as submitted.

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Operational guidance

  • Timing: Update cost basis as soon as possible after an in-kind deposit so downstream reporting reflects accurate lots and gains/loss.
  • Source of truth: Use your internal records (exchange statements, wallet history, or prior custodians’ reports) to determine acquisition dates and basis.
  • Auditability: Retain supporting documentation for the lot inputs used.

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Troubleshooting

Common causes of failures:
IssueCause
Request rejectedLot quantities don’t sum to deposit quantity
Date errorAcquisition date is after the transfer date
Too many lotsMore than 100 lots submitted
Asset mismatchLots don’t match deposit asset type
Unknown assetAsset type not recognized

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Tax terminology

TermOverview
Tax accountTop-level unit used in the API for tax reporting
Tax transactionA tax-relevant event such as a deposit
Gains/lossDifference between sale price and cost basis
InventoryTotal quantity and cost basis of a specific asset type, consisting of multiple tax lots
Tax lotA specific group of units acquired at the same time and cost basis
Acquisition dateDate when an individual gains control of an asset
Cost basisValue of an asset in USD at time of acquisition, used to calculate gains or losses
Cost basis methodMethodology used to compute gains/losses (e.g., HIFO, FIFO, LIFO)
Missing cost basisOccurs when assets are transferred into Anchorage without original acquisition details
Holding periodDuration an asset is held before being sold
Realized gain/lossGains or losses from the sale or disposition of an asset
Unrealized gain/lossGains or losses from price fluctuation not yet realized through a sale