The taxpayer must use form 1040, although itemizing is not necessary.

Only some tankless water heaters currently reach this efficiency level. This is about 20 percent more efficient than the current federal standard. Who gets it? Individuals who install specific energy-efficient home improvements. Energy-efficient refrigerators, clothes washers, and dishwashers. There is no credit for other kinds of electric water heaters.

Fuel savings are calculated as 120,000 miles divided by baseline mpg minus 120,000 miles divided by vehicle mpg.