26 CFR § 301.7507-5 - Earnings.
(a) Availability for tax collection. Earnings of a bank within section 7507(b), whether from segregated or unsegregated assets, which are necessary for, applicable to, and actually used for, payment of depositors' claims under an agreement, are within the immunity of the section. If only a portion or percentage of income from segregated or unsegregated assets is available and necessary for payment of depositors' claims, the remaining income is available for tax collection. Earnings of the bank's first fiscal year ending after the making of the agreement not applicable to payment of depositors will be assumed to be applicable for collection of any tax due prior or subsequent to execution of the agreement. Earnings of subsequent fiscal periods from unsegregated assets not applicable to depositors' claims will be assumed to be applicable to payment of taxes as to which immunity under the section has not previously attached. Earnings from segregated assets are available for collection of tax, whether previously uncollectible under the section or not, after depositors' claims against such assets have been paid in full. See paragraph (a) of § 301.7507-3 and paragraph (a) of § 301.7507-9.
(b) Tax computation. The fact that earnings of a given year may be wholly or partly unavailable under section 7507 for collection of taxes does not exempt the income for that year, or any part thereof, from tax liability. The section affects collectibility only, and is not concerned with taxability. Accordingly, the taxpayer's income tax return shall correctly compute the tax liability, even though in the opinion of the taxpayer it is immune from tax collection under the section. The tax shall be determined with respect to the entire gross income and not merely with respect to the portion of the earnings out of which tax may be collected. As to establishment of immunity from tax collection see § 301.7507-7.
(2) In the year 1955, the earnings are again $10,000, $4,000 from segregated and $6,000 from unsegregated assets, as in 1954. However, the return filed shows income of $5,000 and a tax liability of $1,500. An investigation shows the true income to be $10,000, on which the tax is $3,000. The full $3,000 will be assumed to be collectible. The $600 difference between $3,600 (the excess of earnings from unsegregated assets over the amount going to the depositors), and the $3,000 tax for 1955, is not available for collection of the tax for prior years, which became immune as described above, but may be available for collection of tax for subsequent years.
(c) No significance attaches to the selection of the years 1954 and 1955 in the example set forth in paragraph (b) of this section. The rules indicated by the example are equally applicable to subsequent or prior years not excluded by limitations.