Part IV, Chapter V (Withholding from the Income of Nonresidents or Corporations) of the new Act applies to domestic source income prescribed in Article 212, paragraph (1) (Obligation to Withhold Taxes) of the new Act (excluding that prescribed in the following paragraph), or to interest and similar income, dividends and similar income, distributions of profits, or compensation or fees prescribed in paragraph (3) of that Article, which are to be paid on or after the effective date, and the provisions then in force continue to govern such domestic source income, or such interest and similar income, dividends and similar income, distributions of profits, or compensation or fees, which are to be paid before that date.