What is the threshold for registration in GST?

A person having business which has aggregate
turnover of more than Rs. 20 lakhs calculated for a given PAN
across the country would need to register under GST. There
are some exceptions to this rule as mentioned in section 24 of
the CGST Act, 2017. Aggregate turnover is defined in section
2(6) of the said Act.
For example, assume that a taxable person’s business is in
many States on same PAN. All supplies are below Rs. 10 lakhs
but collectively they are above Rs. 20 lakhs. He would be
required to register under GST.