California Code, Public Resources Code - PRC § 4129.1

When the incorporation of a city removes land from a state responsibility area and the county continues to provide residential fire service for the newly incorporated city and remains under contract to provide fire service for the state responsibility area, the county shall, during the three years subsequent to incorporation, contract with the city to continue to provide fire service to the area removed from the state responsibility area under the same terms and conditions as under the state contract.  The county may bill the newly incorporated city for actual revenue lost under the state contract because of removal of land from the state responsibility area during that period, but may not, during the three-year period, require the city to pay an amount greater than that apportioned for the affected area under the state contract.

If the budget of the department is revised to reflect the removal of the affected lands from a state responsibility area and payments to the county are accordingly reduced, the county may bill the newly incorporated city for the allocable decrease, or if the amount cannot be readily ascertained, the county may, after the effective date of the new budget, charge the city an amount equal to the total payment to the county divided by the total acres of the state responsibility area times the removed acres which are annexed to the city.

This section does not change any power, duty, or responsibility of the department.  This section does not require the department to base its budget on per acre costs and does not impose any requirement that the department implement or design any formula or budget.

This section applies only in counties with a population greater than 8,000,000.