Energy Tax Credit?

If I took a $1000 tax credit in 2006 towards making my home more energy efficient, can I still take an $800 tax credit for 2007 for additional energy efficient windows and doors that were installed?

Ooops! The tax credit was actually 10% of $1000, which was the cost of the added insulation. The $800 was the total cost of the windows and door.

No, based on how your question reads you've already exceeded what was allowed, but thats without knowing what improvements you were actuallyclaiming:

The maximum amount of homeowner credit for all improvements combined is $500 during the two year period of the tax credit.
Note: with the exceptions of Efficient Cars, Solar Energy Systems, and Fuel Cells.

see the source below and the associated links in the text for the chart that lists the limits for specific items.

The $2000 limit applies to Homebuilders not Homeowners

Look at the form.

I don't know what you added in 2006. Water Heater?

For things like windows, it was a maximum of $200 over the two years.

For insulation, it was a maximum of $500 (including the windows) over the two years.

the tax credit was limited to $2000 for all items, but it's based on maybe 10-20% of specific items with a limit on each one - I put in $11K worth of triple pane windows in 2006 - I was only able to deduct around $200 tax credit - I hope you did your return right last year or you can expect an audit, with penalties and interest - the $1000 credit seems high unless you put in around 30,000 of lots of different kinds of energy saving items

If you actually managed to fudge your return to get a $1,000 credit, then it's only a matter of time that the IRS will catch up to you.

The maximum credit for all years is $500. Therefore, you cannot take another credit of $800, and you should probably amend your 2006 return. The link below explains that information.