Secrecy of declaration protects voluntary disclosure particulars from compelled production, with limited official access for tax execution and audit. The provision treats all particulars in a voluntary disclosure declaration as confidential and protects them from compelled production or compelled testimony, while permitting disclosure only to officers executing the Income tax Act or the Wealth tax Act or to officers appointed by the Comptroller and Auditor General or the Board to audit income tax receipts or refunds.