Moving to the UK with US permanent Residency

So my husband, who is a British citizen, now has unconditional permanent residency in the US. We're moving back to the UK. What will happen to his permanent residency? Will he lose it? I wish we would have gone through the citizenship route, but he had been so concerned about having to renouce his UK citizenship (which we do more clearly understand now).  I just hate the thought of wasting all that money, especially if we ever move back to the US and he would have to start it all over again.  Any advice??

I think he will lose it if he stays out of the US for more than a year.   Also, I think even though he is not a US citizen, he will still have to file US tax returns every year for a certain period of time.

My husband has it as well.  My understanding is that after 12 months of being out of the country you lose your green card.  I think that technically it should be surrendered when you move.  We are not notifying them of an address change until after I get over there in September though, and will turn the card in then.

While it may seem expensive to face the cost of returning to the US, just remember that if he were a citizen then both of you would always be required to file tax returns in the US.  It may end up being cheaper for him to not be a citizen and just go through the immigration hassle again, if needed.  (Although, as a side note, I believe guya posted some info on permanent residents being considered domiciled in the US and having to file taxes for 10 years after leaving if they had been there for 8 of the previous 15 years - maybe). 

You may find that Immigration (IE:IO's) will question any absence from 90 days to 6 months............the 1 year rule is arbitrary and generally only accepted for dire reasons (death in the family leading to hardship, estates needing to be sorted etc) it's a judgement call......if USCIS feels as though it's a frivolous reason (someone can't make u p their mind?)  that person may well have to apply again.......the ruling is "up to one year", it's not an iron clad guarantee, anyone looking to retain "unconditional" status needs to be cognizant of this.Their reasoning is based on someone coming to the States, working for 6 months, then going home, returning, going home etc....it's not always the case ,but they definitely question it.