Dear friend,

For doing M tech from NITs you should fill counseling form for getting admission into NITs which will be filled within 10 to 15 days after GATE 2019 official result.

For doing M. tech from IITs you should apply for individual IITs form like IIT Delhi, IIT Mumbai, IIT Madras etc. All IITs M.tech application form will be out in the month of March 2019 to April 2019. So you should be aware of the forms by regular surfing on the internet.

I will provide the link where you can check the cutoff marks

https://engineering.careers360.com/articles/gate-cutoff-for-nits