Rev. Rul. 54-154

Federal tax liens attach to property only to the extent of the delinquent taxpayer's interest therein. Where a taxpayer has only an option to purchase real property at the time the Federal tax lien arises, the lien attaches to the option and not to the real estate. Where his rights under the option are terminable, the Government's rights, by virtue of its lien upon the taxpayer's interest, are likewise terminable, being no greater than those of the taxpayer. Accordingly, when the taxpayer's rights under an option terminate after the Federal tax lien has arisen, the rights of the United States in the option also terminate, since there is no longer any property in the option to which a lien can attach.