The tax provided for in this Ordinance shall be levied, collected and paid with respect to the salaries, wages, commissions and other compensation, and with respect to the net profits of businesses, professions and other activities, earned from the effective date of this Ordinance, and shall apply to all taxes, filings and assessments effective and beginning with tax year 2002. Provided, however, that where the fiscal year of the business, professions or other activity differs from the calendar year, the tax shall be applied to that part of the net profit for the fiscal year as shall be earned on and after January 1, 2002, to the close of the taxpayer’s fiscal year; thereafter the taxpayer shall report on its fiscal year basis.