Check this out:
http://blog.saginfotech.com/gst-due-dates-e-filing-of-tax-return
GST Forms GST Due Dates GST Filing Last Dates Associated Tax Payers
GSTR 1 10th of Next Month 10th October, 2017 Normal or Composite Dealers
GSTR 1A – – Outward supply details of Business unit Corrected or Deleted
GSTR 2 15th of Next Month 15th October, 2017 Normal Dealers Purchase Register
GSTR 2A – – Inward supply reconciliation in Form GSTR-1 by supplier to business
GSTR 3 20th of Next Month 20th October 2017 Normal Dealers Monthly Return
GSTR 3A – – Notice on failure of returns furnishing to registered taxpayer
GSTR 3B 20th of Next Month (Only for July & August) July – 20th August & August – 20th September All Dealers
GSTR 4 18th of Next Quarter 18th October, 2017 Composite Dealers
GSTR 4A Inward supplies reconciliation under composition scheme in form GSTR-1 as supplier furnished
GSTR 5 20th of Next Month 20th October 2017 Non Resident
GSTR 6 13th of Next Month 13th October, 2017 Input Service Distributors
GSTR 6A Inward Supplier reconciliation by ISD in form GSTR-1 as supplier furnished
GSTR 7 10th of Next Month 10th October, 2017 TDS Returns
GSTR 7A Certificate of TDS
GSTR 8 10th of Next Month 10th October, 2017 E-Commerce Operators
GSTR 9 31st December of Next F.Y. Registered Taxable Person
GSTR 9A 31st December of Next F.Y. Taxpaying compounding of Annual return
GSTR 10 Within three months of the date of cancellation or date of cancellation order, whichever is later Final Return for the taxpayer after surrendering or cancellation of the registration
GSTR 11 28th of Next Month 28th October, 2017 Inward supplies statement for person having UIN