National Internal Revenue Code (NIRC)
Section 81. Filing of Return and Payment of Taxes Withheld. - Except as the Commissioner otherwise permits, taxes deducted and withheld by the employer on wages of employees shall be covered by a return and paid to an authorized agent bank; Collection Agent, or the duly authorized Treasurer of the city or municipality where the employer has his legal residence or principal place of business, or in case the employer is a corporation, where the principal office is located.
The return shall be filed and the payment made within twenty-five (25) days from the close of each calendar quarter: Provided, however, That the Commissioner may, with the approval of the Secretary of Finance, require the employers to pay or deposit the taxes deducted and withheld at more frequent intervals, in cases where such requirement is deemed necessary to protect the interest of the Government.
The taxes deducted and withheld by employers shall be held in a special fund in trust for the Government until the same are paid to the said collecting officers.