(1) The commission shall assess the expenses reasonably attributable to investigation and hearing regarding an application filed under section 57-1405, including expenses billed by agencies filing reports as required in subsection (3) of section 57-1407 and both direct and indirect expenses incurred by the commission or its staff or consultants, to the applicant as agreed under section 57-1405.

(2) The commission shall ascertain the expenses of any such investigation and hearing and by order assess such expenses against the applicant and shall render a bill therefor, by United States mail, to the applicant, either at the time the order under section 57-1408 is issued or from time to time during such application process. Such bill shall constitute notice of such assessment and demand of payment thereof. Upon a bill rendered to such applicant, within fifteen days after the mailing thereof, such applicant shall pay to the commission the amount of the assessment for which it is billed. The commission shall remit the payment to the State Treasurer for credit to the Public Service Commission Pipeline Regulation Fund. The commission may render bills in one fiscal year for costs incurred within a previous fiscal year. The commission shall direct the State Treasurer to credit any reimbursement of expenses billed by agencies pursuant to subsection (3) of section 57-1407 to the appropriate fund of the appropriate agency.

(3) If any applicant against which an assessment has been made pursuant to this section, within fifteen days after the notice of such assessment, (a) neglects or refuses to pay the same or (b) fails to file objections to the assessment with the commission as provided in subsection (4) of this section, the commission shall transmit to the State Treasurer a certified copy of the notice of assessment, together with notice of neglect or refusal to pay the assessment, and on the same day the commission shall mail by registered mail to the applicant against which the assessment has been made a copy of the notice which it has transmitted to the State Treasurer. If any such applicant fails to pay such assessment to the State Treasurer within ten days after receipt of such notice and certified copy of such assessment, the assessment shall bear interest at the rate of fifteen percent per annum from and after the date on which the copy of the notice was mailed by registered mail to such applicant.

(4) Within fifteen days after the date of the mailing of any notice of assessment under subsection (2) of this section, the applicant against which such assessment has been made may file with the commission objections setting out in detail the ground upon which the applicant regards such assessment to be excessive, erroneous, unlawful, or invalid. The commission shall determine if the assessment or any part of the assessment is excessive, erroneous, unlawful, or invalid and shall render an order upholding, invalidating, or amending the assessment. An amended assessment shall have in all respects the same force and effect as though it were an original assessment.

(5) If any assessment against which objections have been filed is not paid within ten days after service of an order finding that such objections have been overruled and disallowed by the commission, the commission shall give notice of such delinquency to the State Treasurer and to the applicant in the manner provided for in subsection (3) of this section. The State Treasurer shall then collect the amount of such assessment. If an amended assessment is not paid within ten days after service of the order of the commission, the commission shall notify the State Treasurer and the applicant as in the case of delinquency in the payment of an original assessment. The State Treasurer shall then collect the amount of such assessment as provided in the case of an original assessment.