(4) Subject to the other provisions of this rule and of rule 18.—
(a) (i) every registered dealer who is a retailer and who has opted for composition of tax under sub-section (l) of section 42 shall file a six monthly return within twenty-one days from the end of the period of six months to which the return relates;
(ii) every registered dealer to whom the Explanation to clause (8) of section 2 applies, if his tax liability during the previous year was rupees one crore or less, shall file an annual return within twenty-one days from the end of the year to which such return relates.
Provided that nothing in this paragraph shall apply to the said registered dealer unless he applies to the Joint Commissioner of Sales Tax (Returns), in Mumbai or as the case may be Joint Commissioner of Sales Tax (VAT Administration) in rest of the State;
Read more: MVAT circular on Periodicity of return filing for the period 01.04.09 to 31.03.10 http://taxguru.in/goods-and-service-tax/mvat-circular-on-periodicity-of-return-filing-for-the-period-01-04-09-to-31-03-10.html#ixzz1hGNGUvx0