Americans made more and saved more in December than they had in years.
The Commerce Department says personal income rose by 2-point-6-percent last month (December).
That's the biggest one-month gain since 2004.
And rather than spending it, people socked it away in savings.
The personal savings rate rose from 4-point-one-percent in November to 6-point-5-percent in December.
The explanation ... according to the Commerce Department ... tax changes had companies paying out dividends and bonuses early.
Don't expect it to last though ... one economist says December's strength will be offset by extra weakness in January.