Re: Capital gains if rent out home???
If you sell within 12 months then no CGT is payable. However, if it takes longer than 12 months and you sell before you come home, you would apportion the period you had it as your PPR vs the period you didn't and pay CGT on the portion attributable to the period during which it wasn't your PPR (there are loads of threads on this for more info).
If you move back into the house after your period in the US, there seems to be an exemption in that you could rent it out for the 5 years, move back into it when you get back and then sell at some other stage in the future without having to pay CGT. The Revenue's Guide to Capital Gains Tax outlines this exemption. I'm not an expert in this area though so if you intended to avail of this exemption, I'd take professional advice on the matter.
You haven't asked about stamp duty but if you have owned the house for less than 2 years by the time you move and rent it out, you may be liable for stamp duty clawback.
Sprite