Extending the Bush tax cuts for all income levels beyond year-end would add a "couple tenths" to US economic growth, while allowing the tax cuts to expire would result in "well over a percentage point" hit, Jan Hatzius, chief U.S. economist at Goldman Sachs told CNBC.

"If everything was allowed to expire, as is the current legislation at the end of this year, that would be a major impact," Hatzius said.