The IRS said this week it will start accepting tax returns from most taxpayers an estimated 120 million households on Jan. 30, about eight days later than originally expected.
But some taxpayers will have to wait until late February or early March to file because of complex tax law changes that went into effect Jan. 1 when Congress passed its last-minute, "fiscal cliff" legislation.
The delay includes those claiming residential energy credits, property depreciation or general business tax credits. The IRS said it needs more time to update forms that require extensive computer programming and testing.
Those delayed deadlines will be posted on the IRS website, www.IRS.gov.