Vat return when monthly?

Dear All,

Please let me know, when to file monthly return instead of Quarterly return under gujarat state?

I know abount the limit of Rs. 60000/- but how that limit is counted whether quarterly oy yearly?

i.e. in 3rd qtr. my vat payt. is 40000/- and in jan i m liable to pay 20000/- then should i file monthly return from jan onwards or not?