Green Card Abandonment
One of the most common misconceptions / mistakes made by expats who obtain a Green Card / PR status is that they believe "once you have it, you have it for life". They jet off to see the world confident that with a GC in hand, they can always come back to the United States.
Unfortunately, this isn't always the case. You see, a GC/Permanent Resident status is 'permanent', as long as you are a 'resident'.
Leaving the United States starts the clock running on this question: "Has this Permanent Resident ABANDONED residence in the US?" The clock actually starts on day 1 of your vacation, but it doesn't really get to be an issue until you are off US soil for 6 months. If you've been away for less than six months, the burden of proof is on USCIS to show that you haven't been a Permanent Resident. While this is very rare for a single trip, there are times when they get a hint from an anonymous tip, or you say something really really dumb while coming back into the country, and they make a determination that you have abandoned your Permanent Resident status. They take your card at the border and put you back on an airplane to where you came from.
Generally, this doesn't happen.
However, after six months, there is a shift in this process. It is now up to YOU to prove that you HAVE NOT abandoned your PR status. When you come in you have to have a pretty good story, along with evidence of keeping a residence in the USA (i.e. rent payments, utility bills, mortgage payments, bank accounts, tax returns etc.) that would justify in their mind "yea, this person was away for a long period of time, but it was just a long vacation or they had to care for a loved one".
The same will apply if you have made multiple trips outside the United States, returning only for short periods every 6 months.
If you are gone for more than a year, there is a 'de facto' presumption that you have abandoned your GC (not an issue to be proved one way or the other). If you are gone for more than a year, you will probably be pulled into secondary screening at the airport and given a real thorough review of where you have been over the last 12 months.
So, what can you do if you have to be gone more than 12 months.
You can apply--should apply--for a 're-entry permit' (I-131) which will allow you to stay out for up to 2 years (not longer). However, the requirement to maintain a residence in the United States still applies. http://britishexpats.com/wiki/Category:I-131_Re-entry_Permit
This permit must be applied for while you are physically in the United States.
There is also a Returning Resident Visa, called an SB-1. If you have been outside the United States for too long, it may be possible to obtain this visa to allow you to return as a permanent resident. However, it is not easy to obtain. There are also some exemptions you can get if you a) are in the service of the US military or government, b) the clergy, c) working overseas for a US business.
And finally, the one way to guarantee your re-entry: petition for citizenship. However, you should note that the time limits involved in citizenship can also be affected by the time you spend overseas.
This is not a complete guide to the issues of Abandoning your Green Card, but should be considered a warning that you may need to do more research before departing the US for an extended period of time.
I want to Abandon my Green Card
Yea, it's kind of strange, but a change in the tax law requires you to file a tax return for 10 YEARS after abandonment of a Green Card if you meet certain requirements:
You must file a Form 8854 for each of the 10 tax years after the date of your abandonment of your long-term resident status only if:
Failure to file a required Form 8854 in any of the 10 tax years after the date of your termination of residency may result in a $10,000 penalty for each year that the form is required but not filed.
Just because the USCIS no longer recognises you as having a Green Card doesn't mean the IRS feels the same way...