With five more days until the April 17 tax filing deadline, many procrastinators are scrambling to get their documents together. If you're one of them, don't forget to apply for one of the tax credits for energy-efficient home improvements that expired on December 31. Upgrades that are eligible include roofs, windows and doors, heating and air conditioning, insulation, non-solar water heaters and biomass stoves. The credits range from $50 to $300.

You can only claim a tax credit for improvements made to your principal residence; new construction and rentals do not qualify, according to the federal guidelines. Here's a brief overview of the available tax credits, you can find more detailed information on the Energy Star website. The cost of installation is not included and some products must meet Energy Star requirements to qualify.

Heating and air conditioning. Air source heat heat pump, $300; Central air conditioning, $300; Furnaces and hot water boilers, $150 each.
Insulation and other sealants (caulk, weather stripping). Ten percent of the cost, up to $500.
Roofs (metal and asphalt). Ten percent of the cost, up to $500.
Windows, doors and skylights. Ten percent of the cost, up to $500, but windows are capped at $200.
Non-solar water heaters. Gas, oil or propane, or electric heat pump, $300.
Biomass stoves, including pellet stoves. $300.

How to apply
For products "placed in service" in 2011, you need to file the 2011 version of IRS Form 5695 and submit it with your 2011 taxes. On the 1040 form you enter this tax credit from Form 5695 (the residential energy tax credit) on line 52.

Some tax credits remain
Tax credits are still available for several renewable energy sources and will be until the end of 2016. They include geothermal heat pumps, residential wind turbines and solar energy systems installed in existing homes or with new construction. The tax credits are 30 percent of the cost with no upper limit.