To replace the web of indirect taxes, GST has been introduced. Registration is mandatory under GST if:

1. Sales of goods and services are more than 20 lakhs (Rs 10 lakh for North East states) in a financial year.

2. Business is involved in inter-state supplies or supplies via e-commerce.

3. Taxpayers already registered under VAT/service tax also needs to migrate and register under GST. 

The article furthers explains the benefits of GST registration such as claiming input tax credit, ease in paying taxes, paperless compliance of taxes , etc. It also explains the losses to be faced if the business is not registered under GST.

Read more at:

http://economictimes.indiatimes.com/small-biz/policy-trends/heres-how-your-business-needs-to-change-for-gst/articleshow/58995677.cms