{
  "v": 1,
  "requestId": "6ae40cd0-728f-4469-8366-93e8f8713deb",
  "chainId": 1,
  "window": {
    "toBlock": 26048185,
    "fromBlock": 26047887,
    "toBlockHash": "0x4e56a6dcfef3265a8874b5ee86b0b5e6df4d4bc3cc666e5c442c89638985d5c7"
  },
  "answerType": "uint256",
  "answer": "478558",
  "definitions": {
    "answer": "Bitcoin mainnet block height; the last common block, as specified in the request.",
    "window": "The pinned Ethereum window timestamps the request only and is not used to derive the Bitcoin history fact."
  },
  "recipe": {
    "kind": "panel",
    "source": "https://www.irs.gov/pub/irs-wd/202114020.pdf"
  },
  "notes": "Read the U.S. Internal Revenue Service Office of Chief Counsel memorandum 202114020, dated March 22, 2021. Its Background states that block 478,558 was the last common block shared by Bitcoin and Bitcoin Cash; it also gives that block's hash. The answer is the stated Bitcoin mainnet height as a decimal uint256."
}