Amends GS 105-153.5 (modifications to adjusted gross income) as title indicates.  Adds to subsection (b) (other deductions) new subdivision (7a) allowing small businesses, as defined, to deduct a percentage of revenue used for capital expenditures, also defined, the percentage of which is determined by the amount of adjusted gross income.  Adds to subsection (c) (additions to adjusted gross income) new subdivision (7a) requiring a taxpayer to include the amount deducted in a prior taxable year pursuant to (b)(7a) if the amount was withdrawn and not used to pay for capital improvements. 

Effective for taxable years beginning on or after January 1, 2021.