As per Assam Vat rule 29
(1)(a) The application for refund as referred to in sub-section (1) of section 50 shall be made in Form-37 within one hundred and eighty days of the end of the relevant tax period:
Provided that an application for refund made after the said period may be admitted by the Prescribed Authority, if he is satisfied that the dealer had sufficient cause for not making the application within the said period.
(b) An application for refund shall be signed and verified as in the case of application for registration in case of a registered dealer.
(c) The Prescribed Authority may reject, any claim for refund if the claim filed appears to involve any mistake apparent on the record or appears to be incorrect or incomplete, based on any information available on the record, after giving the dealer the opportunity to show cause in writing against such rejection.
(d) When the Prescribed Authority is satisfied that the refund claimed is due he shall record an order sanctioning the refund.
(e) When the amount to be refunded is more than rupees one lakh the Prescribed Authority shall take prior approval of Deputy Commissioner before sanctioning such refund. The Deputy Commissioner shall not approve the refund if the amount to be refunded exceeds rupees three lakhs but forward such cases to the Commissioner for approval.
Where the amount to be refunded is more than fifteen lakhs, the Commissioner shall take prior approval of the Government before sanctioning such refund.
(f) When an order for refund is passed refund voucher in Form-38 shall be issued in favour of claimant if he desires payment in cash and advice in Form-39, shall, at the same time be forwarded to the Treasury Officer concerned.
(g) Where any amount refundable under this sub-rule is not refunded to the dealer within the period of ninety days, the refund voucher shall include the interest specified under section 52 covering the period following the end of the said period to the day of refund. The authority issuing such order shall simultaneously record an order sanctioning the interest payable, if any, on such refund, specifying therein, the amount of refund, the payment of which was delayed, the period of delay for which such interest is payable and the amount of interest payable by the State Government and shall communicate the same to the Commissioner stating briefly the reasons for the delay in allowing the refund:
Provided that in computing the period of ninety days, the following periods shall be excluded:-
(i) any delay attributable to the conduct of the person to whom the refund is payable; and
(ii) the time during which any reasonable inquiry relating to the return or claim was initiated and completed and the time taken for adjustment by the refunding authority of any tax, interest and other amount due. (h) After the refund is sanctioned if the claimant desires to adjust the amount of refund due to him, the Prescribed Authority shall set off the amount to be refunded or any part thereof against the tax, if any, remaining payable by the claimant or against the future dues.
(i) The Prescribed Authority shall enter in a register in Form-40 particulars of all the refunds allowed in pursuance of assessment orders, all applications for refunds and of the order passed thereon.
(2) Refund of input tax credit carried over for a period of exceeding twenty four months under sub-section (2) of section 50.
(a) Where any excess tax credit for any tax period is carried over for adjustment against the tax due in subsequent tax period or periods and such credit or part thereof remains unadjusted even after a period of twenty four months from the date of filing the return showing excess input tax credit, the dealer may exercise option for further carry forward of the credit till final adjustment or may claim refund of the amount of such excess credit remaining unadjusted.
(b) A registered dealer making sale of goods in the course of inter-state trade or commerce falling under Section 3 of the Central Sales Tax Act, 1956 (Central Act 74 of 1956) shall adjust any excess credit available under the Act against any tax payable under the Central Sales Tax Act, 1956 and thereafter, be eligible to claim a refund of excess credit, only after twenty four continuous credit returns have been filed.
(c) Where a dealer opts for refund of such excess credit, he shall make an application in Form-41 in this behalf within one month from the date of the expiry of the period of twenty four months:
Provided that an application for refund made after the period of one month may be admitted by the Prescribed Authority, if he is satisfied that the dealer had sufficient cause for not making the application within the said period.
(d) The refund under this sub rule shall be subject to the provisions of clause (c), (d), (e), (f), (g), (h) and (i) of sub rule (1).