(ii) Taxpayer without applicable financial statement. A taxpayer electing to apply the de minimis safe harbor may not capitalize under § 1.263(a)-2(d)(1) or § 1.263(a)-3(d) nor treat as a material or supply under § 1.162-3(a) any amount paid in the taxable year for property described in paragraph (f)(1) of this section if—
(A) The taxpayer does not have an applicable financial statement (as defined in paragraph (f)(4) of this section);
(B) The taxpayer has at the beginning of the taxable year accounting procedures treating as an expense for non-tax purposes—
(1) Amounts paid for property costing less than a specified dollar amount
since it would seem you did not have such an accounting policy in place, in my opinion you cannot retroactively elect safe harbor
Importantly, making the election is not considered a change in accounting method. No need to file a Form 3115 Application for Change in Method of Accounting, then. However, it is still important to maintain adequate records and to adhere to the accounting procedures necessary to account for the amounts incurred.
