appeal against notice of demand u/s 156

Yes, 20% and if you wish not to deposit then write a letter to respective AO with support of case laws and wait for there response.

Yes 20% but not mandatory. you can file a stay application with AO but he has no power to waive the requurement and he needs approval of Principal CIT for the same which he will not seek practically. AO has to disposale the stay in 14 days and then you can approach Principal CIT for the waiver directly with detailed application. Rest we can discuss over call if you want. I am a delhi based CA - 9891091307

thanks..

For appeal for exempt income of NRI, under which section we can go for appeal

we can speak at 9891091307