Gifting Property in India to Family Member (SON) ?

You should seek the advice of an estate planning attorney to help you with actually doing this properly. But I will give you some general information.

US green card holders are largely treated the same as US citizens for US tax purposes.

Gifts received. are not subject to US income tax. I.R.C. 102(a).  https://www.law.cornell.edu/uscode/text/26/102

The US does not have an federal inheritance tax (on receiving not making a gift) so that is not an issue. A few US states have a state-level inheritance tax. So if the son lives in Iowa, Kentucky, Maryland, Nebraska, New Jersey, or Pennsylvania that might apply. https://www.thebalancemoney.com/state-inheritance-tax-chart-3505460

Gifts received from outside the US worth more than $100k must be reported on IRS Form 3520. This is not a tax, just reporting. https://www.irs.gov/forms-pubs/about-form-3520

The parents will be using up some of their $12 million each estate/gift tax exclusion. They will need to file an IRS Form 709 will need to be filed to keep track of that. 

It is also possible that there will be some ongoing (yearly) information reporting of the foreign asset. I am not sure about that for real estate. If the asset is held in an entity (corporation, trust, etc.) that would be another reporting possibilty.

Also note that if the property is sold by the son, his "basis" or cost will be whatever the parent's basis or cost was at the time of the gift. This is called carryover basis. When sold his gain would be sales price - cost of sale - parents cost basis - any capital improvements made by the son.

If instead the son were to inherit the real estate when the parents dies, he would get a step-up in basis to the fair-market value as of the date of inheritance (death) and therefore not have to pay income tax (capital gains tax) if he were to sell. (because step-up basis is usually much higher than carryover basis). But of course there can be plenty of non-income tax reasons for doing such a transfer while the parents are still living.

I hope that helps a little. Be certain to obtain the advise of a profession such as an estate planning attorney who has worked in this area before to help you will the details and application to your specific facts.

@P--GUPTA , agreeing with the general & correct information provided by @jtax ,  and assuming that you are the receiving party ( US citizen )  and donor is your father ( Green Card ), 

(a) for Us tax purposes  this is a gift between two US persons and that the asset is located in a foreign country is immaterial.

(b) since India does have inheritance , gift and asset taxation -- there may be implication there -- should seek  professional help in Inida.

(c) as mentioned by @jtax , the basis of the asset transferred  ( for US purposes only ) is the  basis of the donor at the time of the transaction i.e. acquisition cost of the donor  LESS any depreciation allowable under US tax laws PLUS  cost of any improvements allowable per US laws.    Unlike India  US does not index  the basis .

(d) Your  gain when disposing per US laws  would be  Sales Price reduced by allowable sales expenses ( including  commission, transfer tax etc. ) LESS your basis  in the asset.  Obviously India would charge its own capital gains taxes which now would be eligible  for foreign tax credit against the  sales proceeds ( foreign  income).

(e) As you can see form the above gifting is not necessarily the best choice for  donee/recipient -- inheritance results in  basis adjustment to fair market value on the date of demise of the decedent.

(f) Also because this transaction is between two US persons, the value of the asset so gifted would count against the donor's  free estate tax limit when the donor's  estate comes to probate.  The donor has to file form 720 with his return to recognize the transfer of ownership.

That is my three cents worth.

Namaste ji

pk