26 CFR §1.172-5

1. (a)Taxable year subject to the Internal Revenue Code of 1954. The taxable income for any taxable year subject to the Internal Revenue Code of 1954 which is subtracted from the net operating loss for any other taxable year to determine the portion of such net operating loss which is a carryback or a carryover to a particular taxable year is computed with the modifications prescribed in this paragraph. These modifications shall be made independently of, and without reference to, the modifications required by §§ 1.172-2(a) and 1.172-3(a) for purposes of computing the net operating loss itself.
   1. (1)Modifications applicable to unincorporated taxpayers only. In the case of a taxpayer other than a corporation, in computing taxable income and adjusted gross income:
      1. (i)No deduction shall be allowed under section 151 for the personal exemptions (or under any other section which grants a deduction in lieu of the deductions allowed by section 151) and under section 1202 in respect of the net long-term capital gain.
      2. (ii)The amount deductible on account of losses from sales or exchanges of capital assets shall not exceed the amount includible on account of gains from sales or exchanges of capital assets.
   2. (2)Modifications applicable to all taxpayers. In the case either of a corporation or of a taxpayer other than a corporation:
      1. (i)Net operating loss deduction. The net operating loss deduction for such taxable year shall be computed by taking into account only such net operating losses otherwise allowable as carrybacks or carryovers to such taxable year as were sustained in taxable years preceding the taxable year in which the taxpayer sustained the net operating loss from which the taxable income is to be deducted. Thus, for such purposes, the net operating loss for the loss year or any taxable year thereafter shall not be taken into account.
      2. (ii)Recomputation of percentage limitations. Unless otherwise specifically provided in this subchapter, any deduction which is limited in amount to a percentage of the taxpayer's taxable income or adjusted gross income shall be recomputed upon the basis of the taxable income or adjusted gross income, as the case may be, determined with the modifications prescribed in this paragraph. Thus, in the case of an individual the deduction for medical expenses would be recomputed after making all the modifications prescribed in this paragraph, whereas the deduction for charitable contributions would be determined without regard to any net operating loss carryback but with regard to any other modifications so prescribed. See, however, the regulations under paragraph (g) of § 1.170-2 (relating to charitable contributions carryover of individuals) and paragraph (c) of § 1.170-3 (relating to charitable contributions carryover of corporations) for special rules regarding charitable contributions in excess of the percentage limitations which may be treated as paid in succeeding taxable years.
      3. (iii)Minimum limitation. The taxable income, as modified under this paragraph, shall in no case be considered less than zero.
   3. (3)Electing small business corporations. For special rule applicable to corporations which were electing small business corporations under Subchapter S (section 1361 and following), Chapter 1 of the Code, during one or more of the taxable years described in section 172(b)(1), see paragraph (f) of § 1.172-1.
   4. (4)Qualified real estate investment trust. Where a net operating loss is carried over to a qualified taxable year (as defined in § 1.172-10(b)) ending after October 4, 1976, the real estate investment trust taxable income (as defined in section 857(b)(2)) shall be used as the “taxable income” for that taxable year to determine, under section 172(b)(2), the balance of the net operating loss available as a carryover to a subsequent taxable year. The real estate investment trust taxable income, however, is computed by applying the rules applicable to corporations in paragraph (a)(2) of this section. Thus, in computing real estate investment trust taxable income for purposes of section 172(b)(2), the net operating loss deduction for the taxable year shall be computed in accordance with paragraph (a)(2)(i) of this section. The principles of this subparagraph may be illustrated by the following examples:
2. (b)[Reserved]