The Economic Survey 2018 estimates that GSTN implementation has increased the indirect taxpayer base by more than 50 per cent, with 3.4 million businesses coming into the tax net 12. It appears that the number of GST registrants has risen due to a large increase in voluntary registrations. Small B2C firms want to be part of the GSTN because they buy from large enterprises.
In fact, 68 percent of 12  ibid  8  their purchases are from medium or large registered enterprises, giving them a powerful incentive to register, so they could secure input tax credits on these purchases. The Input Tax Credit motivation is a strong push towards digitisation and formalisation of small businesses.