From the NYT
Even though he has not released his returns from earlier years, the 2010 return sheds some light on those years.
That’s because Mr. Romney paid income tax to foreign countries, and as result claimed in 2010 a $129,697 foreign tax credit, which he used to offset taxes he owed in the United States. American taxpayers who claim the foreign tax credit are required to report their total foreign taxes paid and tax credits used for the previous 10 years. So that return contains foreign tax data going back to 2000.
The good news for Mr. Romney is the forms suggest that he paid at least some federal income tax every year, as he has said he did. He used the foreign tax credit every year to offset his taxes in the United States, and American taxpayers can’t use a tax credit if they owe no federal income tax. This casts even more doubt on the claim by the Senate majority leader, Harry Reid, attributed to an unnamed Bain Capital source, that Mr. Romney paid no income taxes during that time.