(b) Definitions. — For purposes of this section, the term:

1. (1) "Eligible taxpayer" means a utility which has provided electric, natural gas, water, or sewer utility service, or any combination of electric, natural gas, water, or sewer utility services, to qualified low-income residential customers at special reduced rates.
2. (2) "Cost of providing electric or natural gas or water or sewer utility service, or any combination of electric, or natural gas, or water, or sewer utility services, at special reduced rates" means the amount certified by the Public Service Commission under the provisions of §24-2A-2 of this code, as the revenue deficiency incurred by a public utility in providing special reduced rates for electric or natural gas or water or sewer utility service, or any combination of electric, natural gas or water or sewer utility services, as required by §24-2A-1 of this code or authorized by §24-2A-5 of this code.
3. (3) "Special reduced rates" means the rates ordered or approved by the Public Service Commission under the authority of §24-2A-1 or §24-2A-5 of this code.
4. (4) "Qualified low-income residential customers" means those utility customers eligible to receive electric, or natural gas, or water or sewer utility service, or any combination of electric, natural gas, or water or sewer utility services, under special reduced rates.

(c) Amount of credit. —

1. (1) For tax years beginning prior to January 1, 2019, the amount of the credit available to any eligible taxpayer shall be equal to its cost of providing electric, or natural gas, or water utility service, or any combination of electric, natural gas, or water utility services, at special reduced rates to qualified residential customers, less any reimbursement of said cost which the taxpayer has received through any other means.
2. (2) For tax years beginning on or after January 1, 2019, the amount of the credit available to any eligible taxpayer shall be equal to its cost of providing electric, or natural gas, or water or sewer utility service, or any combination of electric, natural gas, water or sewer utility services, at special reduced rates to qualified residential customers, less any reimbursement of said cost which the taxpayer has received through any other means.

(d) When credit may be taken. — An eligible taxpayer may claim a credit allowed under this section on its annual return for the taxable year in which it receives certification of the amount of its revenue deficiency from the Public Service Commission.

Notwithstanding the provisions of §11-24-16 of this code to the contrary, no credit may be claimed on any declaration of estimated tax filed for such taxable year prior to July 1 of such taxable year. Such credit may be claimed on a declaration or amended declaration filed on or after that date but only if the amount certified will not be recovered by application of the business and occupation tax credit allowed by §11-13-3f of this code. In such event, only that amount not recovered by that credit may be considered or taken as a credit when estimating the tax due under this article. In no event may the eligible taxpayer recover more than 100 percent of its revenue deficiency as certified by the Public Service Commission.