I will be working abroad for two years. I still maintain a home in nj and will return summers. Am I liable for inome earned abroad.

For the federal return, you must file, but you can claim the Foreign Earned Income Exclusion by submitting Form 2555 for up to about $91K of income. If you are earning more than that, you can claim the Foreign Tax Credit for foreign income taxes paid to the host country.

For New Jersey, I believe you WILL be liable for New Jersey income taxes. The fact that you are maintaining a home in NJ to which you will be returning for summer occupancy clearly shows you are maintaining NJ residency, and New Jersey, like every other state in the Union, requires you pay taxes on ALL world-wide income. I do not think they recognize the Foreign Earned Income Exclusion nor the Foreign Tax Credit.