We ordered external windows for our entire home in Dec 2022. We paid a deposit in Dec 2022 and paid the remaining balance in Feb 2023 once the windows were installed. Should we claim the deposit only on our 2022 taxes and next year claim the remaining that was paid in 2023?
No, you should file for the credit in 2023.
Please see the IRS instructions for Form 5695:
Costs.
For purposes of both credits, costs are treated as being paid when the original installation of the item is completed, or, in the case of costs connected with the reconstruction of your home, when your original use of the reconstructed home begins. For purposes of the residential clean energy credit only, costs connected with the construction of a home are treated as being paid when your original use of the constructed home begins. If less than 80% of the use of an item is for nonbusiness purposes, only that portion of the costs that is allocable to the nonbusiness use can be used to determine either credit.