Taxability for NRI

He stays here more than 182 days
than he liable for tax to resident in india more than 182 days.

If stay in India is exceeding 182 days , your cousin becomes Resident Indian for tax purposes and like any individual he is taxable on his global income at applicable tax slabs.

Of course he will get DTAA relief for income tax he paid in USA .

@ Shaikh
your cousin is taxable if he stays more than 182 days during the previous year in india. Sec 6 (1)
he is taxable at the pescribed rates as applicable for a resident individual in india.
He will get some DTAA RELIEF..

@ Hannan

To save from Resident status, he should cut short his 10 days stay by 3-4 days .

Thanks for reply @ Sabyasachi @ Pravin @ Hemangi but my actual question is He Stays more than 180 days in USA by the time he come back to India. TAXABILITY for A.Y 20-21??

@ Hannan

a) Please calculate no. of days from - 1-4-2019 to 20-9-2019

b) calculate No of days comes back to India after 21-9-2019

Do ...... a + b

If it exceeds 182 days then your cousin has to pay tax on global income .

He will of course get DTAA relief. About USA taxation , you ask there in USA.