I was mailed a "Tax Rebate Certificate" from my installer. My system was installed in June 2008. Does anyone know how to use this, or if there actually is a tax rebate. I typically use Turbotax, and it does not show any entries for geo. only solar systems, or hybrid cars. There are likely a bunch of people that would be interested in this if it is valid. I'll keep looking elsewhere to see what information is out there. I did find a small thread in this forum under the "US legislative and regulatory" but it did not come to a certain conclusion. Thackery The certificate states the following. "The new law offers a one time tax credit of 30% of the total investment up to amximum creit of $2000.00 for all residential ground loop or ground water geothermal heat pump installations. A credit of 10% of the total investment is also available without a miximum credit limit for commercial installation. To qualify, the systems must meet or exceed Energy Star requirements and be installed after Dec. 31, 2007. Please complet the information below,and keep this certificate for your records. Consult your tax advisor for further information.