The U.S. Internal Revenue Service is considering whether to tax non-fungible tokens (NFTs) on a par with other collectibles such as stamps, works of art and fine wine, in a move likely to have an impact on those including the digital assets within their retirement plan, according to a document published Tuesday.

The proposed guidance represents the first move by the U.S. tax authority in a while to clarify the tax treatment of digital assets, addressing a vacuum that has left some taxpayers guessing about their liability.

The IRS and Treasury are "soliciting feedback for upcoming guidance regarding the tax treatment of a nonfungible token (NFT) as a collectible under the tax law," implying a less favorable treatment under capital gains tax rules, and with implications if the assets are acquired by individual retirement accounts, the statement said.