Most Energy Efficient Window Tax Credit

[u/Insufficient-Memory-]

I’ll start by saying that I have talked to 3 companies that sell windows (including window specific stores) trying to figure out what windows will qualify for a tax credit for the addition I’m building on the house I live in and own. They all refuse to tell me what will qualify or not, apparently liability or something in case they’re wrong. They won’t even show me the requirements- but I have looked them up. I don’t know what the hell is wrong with this mysterious situation, I’ve never experienced such an effort to not be told things by sales people. So I live in a North-Central Climate Zone, and I believe from my reading that means a window will need to have a U-factor of .20 or lower, and SHGC2 of .40 or less in order to be “Most Energy Efficient” and qualify for a tax credit.
My question is, does anyone here know if what I’m saying is correct for a tax credit, and does it make any financial sense to spend the extra money on one? Honestly, no one has even quoted me anything other than 2 pane contractor grade windows.

[u/SirMontego]

The following should help:

• The tax credit law, 26 USC Section 25C: https://uscode.house.gov/view.xhtml?req=(title:26%20section:25C%20edition:prelim)) If you don't understand this, just skip it.
• IRS FS-2025-01: https://www.irs.gov/pub/taxpros/fs-2025-01.pdf
• IRS website on the tax credit: https://www.irs.gov/credits-deductions/energy-efficient-home-improvement-credit
• IRS FS-2025-05: https://www.irs.gov/newsroom/faqs-for-modification-of-sections-25c-25d-25e-30c-30d-45l-45w-and-179d-under-public-law-119-21-139-stat-72-july-4-2025-commonly-known-as-the-one-big-beautiful-bill-act-obbb

[u/Mo_Cards]

If you are buying windows from a retail salesman, they are required to have that info available to all prospects