The BIR form 2307 form is also known as Certificate of Creditable Tax Withheld as Source. This is a certificate that must be completed and supplied to the income subject recipients in order to expand the withholding tax that has been paid by a Withholding Agent or Payor. This form is necessary to apply for the payor in order to withhold the tax agent for the payee. The document is addressed to the EWT paid by the agent.