Form 16 hra calculation

If employers has given HRA (as per pay slip), why they have not incorporated in form 16?

He has 3 form 16 in one they have shown but another 2 didn't shown the hra deduction

Well, if they had provided HRA it would have been incorporated in it. It means they have not given any HRA. In that case you cannot claim it; nor fabricate it.

Only company giving hra doesn't mean you can claim that right, there must be rent know, I'm not asking here to fabricate, I think u didn't understand my situation here, he served in 3 companies one company 3lac sal another 2.5 lac they both didn't bother to claim it another company he had 7lac they have claimed it, and when I gone through every pay slip he have hra and also he's paying 20000 rent,

If the other 2 companies have paid it, ask them to issue form 16 w.r.t. HRA  deductions.

Without form 16, just based on pay slip, your claim will not be entertained by CPC.