Whether or not a billing authority making calculations (whether originally or by way of substitute) anticipates a precept to be issued in accordance with section 41 of the Act to it for that year by a local precepting authority, where the local precepting authority subsequently issues such a precept to the billing authority—
(a) if the precept is first issued before 1st March in the preceding year, or before the billing authority has completed its original calculations for the financial year, which ever is the later, the billing authority shall pay to the local precepting authority a sum equal to the amount of the precept issued (or last issued);
(b) if the precept is first issued on or after 1st March in the preceding year and after the billing authority has completed its original calculations for the financial year, the billing authority shall pay to the local precepting authority a sum equal to the amount which is the lower of the precept issued (or last issued) by it and the highest amount which the billing authority could have anticipated in respect of a precept to be issued by the local precepting authority for that financial year under regulation 2 of the principal Regulations as amended by these Regulations.