Specifics vary, but some credits can be "carried forward," meaning they do not have to used the year they were collected. I have one such credit that can be carried forward three years and I very vaguely remember reading about a credit that be carried for five years.
The Colorado Alt car credit is remarkably generous, refundable, and can be used for used and leased cars too. I don't however know if each year has a cap amount the state is willing to hand out. I'll have to find out as the time to build approaches.
Addendum: Not from the IRS, but here is some verbiage regarding the federal tax return:
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Can I carry over my unused credit amount to a different tax year?
To the extent the credit is treated as a personal credit (i.e., attributable to personal driving) any unused credit can’t be carried over to another tax year. However, to the extent the vehicle is used in the purchaser’s business, a proportionate amount of the credit is treated as a general business credit and the unused business credit can be carried over to another tax year.
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