Here is a list of all the returns to be filed under the GST Law along with the due dates.

For regular business:

GSTR-1: Details of outward supplies of taxable goods and/or services effected.
Interval: Monthly
Due Date: 10th of the next month

GSTR-2: Details of inward supplies of taxable goods and/or services effected claiming input tax credit.
Interval: Monthly
Due Date: 15th of the next month

GSTR-3: Monthly return on the basis of finalization of details of outward supplies and inward supplies along with the payment of amount of tax.
Interval: Monthly
Due Date: 20th of the next month

GSTR-9: Annual Return
Interval: Annually
Due Date: 31st December of next financial year

GSTR-3B: Provisional return for the months of July to December 2017
Interval: Monthly
Due Date: 20th of the next month

For a business/dealer opting to continue with composition scheme:

A composition dealer will enjoy the benefits of lesser returns & compliance along with payment of taxes at nominal rates. A composition dealer will file only 2 returns:

GSTR-4: Return for compounding taxable person
Interval: Quarterly
Due Date: 18th of the month succeeding quarter

GSTR-9A: Annual Return
Interval: Monthly
Due Date: 31st December of next financial year

Returns to be filed by specific registered dealers:

GSTR-5: Return for Non-Resident foreign taxable person
Interval: Monthly
Due Date: 20th of the next month

GSTR-6: Return for Input Service Distributor
Interval: Monthly
Due Date: 13th of the next month

GSTR-7: Return for authorities deducting tax at source.
Interval: Monthly
Due Date: 10th of the next month

GSTR-8: Details of supplies effected through e-commerce operator and the amount of tax collected
Interval: Monthly
Due Date: 10th of the next month

GSTR-10: Final Return
Interval: Once. When registration is cancelled or surrendered
Due Date: Within three months of the date of cancellation or date of cancellation order, whichever is later.

GSTR-11: Details of inward supplies to be furnished by a person having UIN and claiming refund
Interval: Monthly
Due Date: 28th of the month following the month for which statement is filed