Hello JA Customer,
Currently the IRS is offering some credits for certain energy improvements made to your home. This includes the installation of qualifying HVAC equipment, roofs, doors, windows, insulation, water heaters and solar energy systems, but there are no credits being offered for installation of a new septic system of any type.
The cost of the new septic system simply adds to your basis in the home. If the home is ever sold, the cost of this improvement will be part of your basis, thereby reducing any taxable gain you have from the eventual sale of your home.
If this was helpful please press the Accept button. It is the only way we receive any credit for helping with these questions.
Thank you JA Customer