5.1. The amount of the contribution established under section 1.1 is revised during the municipal fiscal year concerned using the following formula:
A × B × (C / D)
A = 53% in 2009 and subsequent years;
B = the sum of the income indicated, as police services charged to the municipalities and the contribution of the Sûreté du Québec, in the income statement filed in the financial statements of the police services fund for the fiscal year of the fund that ended during the municipal fiscal year concerned;
C = the amount of the estimated contribution of a municipality established for the current year in accordance with sections 2 to 5; and
D = the total amount of the estimated contributions of all the municipalities served by the Sûreté du Québec established in accordance with sections 2 to 5.
The amount of the difference between the revised contribution and the contribution established under section 1.1 is added to the contribution for the following municipal fiscal year or subtracted from that contribution, as the case may be. If the municipality no longer receives police services after 1 January of that fiscal year and the amount cannot be added to or subtracted from the contribution, the amount is to be claimed from or refunded to the municipality, as the case may be. That amount in no case bears interest.