What are the tax implications of expatriation (giving up green card)?

H1B holder, have just started the green card application process via my employer, so that my wife can work on her H4, but only intend to stay in the US for a few more years. I am concerned that this may affect my tax bill after I leave the US in ~3 years time. 

Section 887A (“exit tax”) applies to covered expatriates. Covered expatriates are US citizens and long-term residents. Long-term resident is defined under the code as an individual who has held a green card in at least 8 of the 15 years ending with the year of expatriation. So it does not appear that you would be affected by Section 877A.

– Law Office of Kunal Patel, LLC