Income as per income tax differ with gst to

Dear Members,

A person engaged in the business of Service Industry, He opted for presumptive basis U/s 44AD of Income Tax Act, 1961 and shown amount of Rs.30,00,000/- as To & 8% profits he paid Income Tax, But during FY 2017-18 he made sales as per service tax amounts to Rs.3,00,000 & shown 20,00,000 in GSTR-3B & GSTR-1. Is there any future consequences relating to the difference between presumptive income & income actually shown in GST returns that is there is a difference of Rs.7,00,000, what is the treatment for the same under GST.

Thanks & Regards

Ravindra.