--(a) General.-- Every employer required to deduct and withhold tax under this local law shall, for each calendar month, on or before the fifteenth day of the month following the close of such calendar month, file a withholding return as prescribed by the administrator and pay over to the administrator or to a depositary designated by the administrator, the taxes so required to be deducted and withheld, except that for the month of December in any year, the return shall be filed and the taxes paid on or before January thirty-first of the succeeding year. Where the aggregate amount required to be deducted and withheld by any employer under this local law and under any local law imposing a tax on earnings of nonresidents of the city adopted by the city pursuant to authority granted by the general city law is less than twenty-five dollars in a calendar month and the aggregate of such taxes for the semi-annual period ending on June thirtieth and December thirty-first can reasonably be expected to be less than one hundred fifty dollars, the administrator may, by regulation, permit an employer to file a return on or before July thirty-first for the semi-annual period ending on June thirtieth and on or before January thirty-first for the semi-annual period ending on December thirty-first. The administrator may, if he believes such action necessary for the protection of the revenues, require any employer to make a return and pay to him the tax deducted and withheld at any time, or from time to time. Where the amount of wages paid by an employer is not sufficient under this local law and under any local law imposing a tax on earnings of nonresidents of the city adopted by the city pursuant to authority granted by the general city law to require the withholding of tax from the wages of any of his employees, the administrator may, by regulation, permit such employer to file an annual return on or before February twenty-eighth of the following calendar year.

1. (b) Combined returns. The administrator may by regulation provide for the filing of one return which shall include the return required to be filed under this section, together with the employer's return required to be filed under any local law imposing a tax on earnings of nonresidents of the city adopted by the city pursuant to authority granted by the general city law.
2. (c) Deposit in trust for city. Whenever any employer fails to collect, truthfully account for, pay over the tax, or make returns of the tax as required in this section, the administrator may serve a notice requiring such employer to collect the taxes which become collectible after service of such notice, to deposit such taxes in a bank approved by the administrator, in a separate account, in trust for the city and payable to the administrator, and to keep the amount of such tax in such account until payment over to the administrator. Such notice shall remain in effect until a notice of cancellation is served by the administrator.