The White House says U.S. President Barack Obama has signed into law the bill averting the threatened "fiscal cliff" of higher taxes and spending cuts.
The compromise legislation, approved by both houses of Congress on January 1, raises tax rates for wealthy Americans and extends tax cuts for the middle class.
Economists had warned that failure to avoid the "fiscal cliff" could have pushed the United States, the world's biggest economy, back into recession.
World stock markets rallied on January 2 following approval of the legislation.
The U.S. Dow Jones industrial average saw its biggest gain in a year, as Asian and European markets jumped.
However, the International Monetary Fund (IMF) and the Moody's and Standard & Poor's ratings agencies have warned that the U.S. economy will remain on potentially unstable ground until lawmakers take substantive action to reduce the United States' $16.4 trillion debt.
The IMF warned that the legislation does not go far enough to address long-term U.S. deficit and debt problems.
A statement from IMF spokesman Gerry Rice said that without the deal, the U.S. economic recovery "would have been derailed."
But the statement said "more remains to be done to put U.S. public finances back on a sustainable path."
Based on reporting by AP, Reuters, and AFP