Filing of Form 10 by a trust or institution who seeks exemption u/s 11 or u/s 12 is required when it wants to accumulates income . Thus section 11(2) of the Income Tax Act makes it mandatory for all persons claiming tax exemption us. 11 & Section 12 to intimate the assessing officer the particulars required in Form No. 10. The relevant rule is Rule 17 of Income Tax Rule.