GST is the product of the biggest tax reform in India which has tremendously improved ease of doing business and increasing the taxpayer base in India by including millions of small businesses.GST registration applies to all individuals and entities supplying goods or services in India. GST registration becomes mandatory when the aggregate value of supply exceeds Rs.20 lakh. The Ministry of Finance (MoF) simplified the GST registration procedure to ease the tax filing process. If the entity operates in a special category state, GST registration becomes applicable if the value exceeds Rs.10 lakh p.a. 
Filing of GST Returns is an obligation which needs to be fulfilled by all businesses under the GST regime. Dealers registered under GST have to file annual and monthly returns which can be done through a simple online procedure. GST Return is a document mentioning details of income a taxpayer is required to file with the concerned tax authority on the basis of which the tax liability will be determined. A registered dealer needs to file GST returns entailing Purchases, Sales, Output GST (on sales) and Input tax credit (GST paid on purchases). The various kinds of GST returns filed by taxpayers are GSTR - 1, GSTR - 2, GSTR - 2A, etc.
All the individuals and entities who qualify under the eligibility criteria are mandated to go through GST Registration. Defaulters who fail to comply with the rules and do not pay the tax or make short payments (genuine errors) instead of full payment are liable to pay a penalty. The penalty for tax evasion by an offender will be 100% of the tax amount due. The amount to be paid as penalty for not registering under GST is 10% of the total tax amount due subject to a minimum of Rs. 10,000.