Who is responsible to deduct TDS

As per Section 51 CGST (Central Goods and Services Tax) Act 2017, provides that
1.A department or establishment of Central Govt or State Govt, or
2.local authority or
3.Govt Agencies or
4.other specified persons are required to deduct
TDS @ 2% (IGST 2%, or CGST 1% + SGST 1%)
from the payment made or credited to supplier,
for supply of taxable goods or services or both

Again as per Central Board of Indirect Taxes and Customs Notification No. 50/2018 dated the 13th September, 2018
following entities are also required to deduct TDS
5.An authority or a board or any other body which has been set up by Parliament or a State Legislature or by a government, with 51% equity ( control) owned by the government.
6.A society established by the Central or any State Government or a Local Authority and the society is registered under the Societies Registration Act, 1860.
7.Public sector undertakings.

What is the threshold limit
where the total value of such supply under a contract is more than Rs 2.50 lacs.To compute the limit the GST separately mentioned in the invoice will not count.
When the location of supplier and place of supply is different from place of the recipient no deduction of TDS is required

When to pay TDS certificate and return
TDS shall be paid to Goverrnment after the 10th day of every month.
The person deducting tax is required to file a TDS return in form GSTR-7 within 10 days from the end of the month.
The person deducting tax has to issue the TDS certificate in form GSTR-7A to the concerned person within 5 days of depositing the tax to the government. Failure to do so will make the person liable to pay a late fee of Rs. 100 per day up to a maximum of Rs. 5000.

Sec 51 of CGST Act
Notification no.50 dt 13.09.18