Employers - Social Security, Medicare and withheld income tax. File for 941 for the first quarter of 2009. This due date applies only if you deposited the tax for the quarter in full and on time.

Employees - who work for tips. If you received $20 or more in tips during April, report them to your employer. You can use Form 4070.

Employers - Nonpayroll withholding. If the monthly deposit rule applies, deposit the tax for payments in April.

Employers - Social Security, Medicare and withheld income tax. If the monthly deposit rule applies, deposit the tax for payments in April.