You can in fact request a private letter ruling from the IRS. They are not obligated to respond to it, but typically do. E.g. For §25D https://www.irs.gov/pub

You can in fact request a private letter ruling from the IRS. They are not obligated to respond to it, but typically do. E.g. For §25D https://www.irs.gov/pub/irs-wd/201809003.pdf https://www.irs.gov/pub/irs-wd/201809003.pdf https://www.irs.gov/pub/irs-wd/1130003.pdf https://www.irs.gov/pub/irs-wd/1130003.pdf You also apparently did not review https://www.irs.gov/pub/irs-drop/n-13-70.pdf https://www.irs.gov/pub/irs-drop/n-13-70.pdf (Which even has a contact phone number for the author; call it! Worse that can happen is they point you somewhere else.) If you google "IRC §25D" you'll find a wide variety of resources. In reality, what you'd likely do is a read a bit, and try to come to reasonable conclusion. If the tax amount at issue is substantial, try to find someone with expertise in the topic. Also try to take ideas to their logical conclusion. If 25% of your roof is solar panels, do you think the credit should apply to the cost of an entire new roof as well? It's a credit to encourage energy efficiency, not regular upkeep.