February 1, 2010 is the deadline for employers to mail out Form W-2 and for businesses to furnish Form 1099 statements reporting, among other things, non-employee compensation, bank interest, dividends, and distributions from a retirement plan.

January 15 is the deadline to pay your fourth quarter estimated tax payment. However, you can skip this estimated payment without penalty if you file your return and pay your balance in full by February 1, 2010.

Remind employees to complete a new W 4 if the number of dependents, income from other jobs, etc has changed. 

Details are available on the IRS website.