Section 1.57-5 - Records to be kept(a)In general. The taxpayer shall have available permanent records of all the facts necessary to determine with reasonable accuracy the amounts described in § 1.57-1 . Such records shall include:(1) In the case of amounts described in paragraph (a) of § 1.57-1 : the amount and nature of indebtedness outstanding for the taxable year and the date or dates on which each such indebtedness was incurred or renewed in any form; the amount expended for property held for investment during any taxable year during which such indebtedness was incurred or renewed; and the manner in which it was determined that property was or was not held for investment.(2) In the case of amounts described in paragraphs (b), (c), (d), (e), and (h) of § 1.57-1 : (i) The dates, and manner in which, the property was acquired and placed in service,(ii) The taxpayer's basis on the date the property was acquired and the manner in which the basis was determined,(iii) An estimate of the useful life (in terms of months, hours of use, etc., whichever is appropriate) of the property on the date placed in service or an estimate of the number of units to be produced by the property on the date the property is placed in service, whichever is appropriate, and the manner in which such estimate was determined,(iv) The amount and date of all adjustments by the taxpayer to the basis of the property and an explanation of the nature of such adjustments, and(v) In the case of property which has an adjusted basis reflecting adjustments taken by another taxpayer with respect to the property or taken by the taxpayer with respect to other property, the information described in paragraph (a)(2)(i) through (iv) of this section, with respect to such other property or other taxpayer.(3) In the case of amounts described in paragraph (f) of § 1.57-1 , the fair market value of the shares of stock at the date of exercise of the option and the option price and the manner in which each was determined.(4) In the case of amounts described in paragraph (g) of § 1.57-1 , the amount of debts written off and the amount of the loans outstanding for the taxable year and the 5 preceding taxable years or such shorter or longer period as is appropriate.(b)Net operating losses. The taxpayer shall have available permanent records for the first taxable year in which a portion of a net operating loss was attributable to items of tax preference (within the meaning of § 1.56A-2 (b) ) and each succeeding taxable year in which there is a net operating loss or a net operating loss carryover a portion of which is so attributable. Such records shall include all the facts necessary to determine with reasonable accuracy the amount of deferred tax liability under section 56, including the amount of the net operating loss in each taxable year in which there are items of tax preference in excess of the minimum tax exemption (as determined under § 1.58-1 ), the amount of the items of tax preference for each such taxable year, the amount by which each such net operating loss reduces taxable income in any taxable year, and the amount by which each such net operating loss is reduced in any taxable year.T.D. 7564, 43 FR 40479, Sept. 12, 1978, as amended by T.D. 8138, 52 FR 15309, Apr. 28, 1987