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@FrankK wrote:

 The release of the software that I used correctly calculated that no credit was allowable.

A similar example: Are you saying that you only enter the first $10K of SALT from W-2s, even though the actual amount may be greater?  Or that you only enter other data up to the threshold amounts (e.g. mortgage interest) instead of using the deductible mortgage interest worksheet?  What if our friends in Congress retroactively change the law after you enter the "limited" data?

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If the original release of the software told you that no credit was allowed, that was an error in the software, and they appeared to have fixed that.  You seem to have made a mistake by not finding out why it wasn't giving the credit.

I ask the taxpayers for the amounts during the proper time period, which is usually the tax year (but some things like this Adoption credit and the Dependent Care credit stop when a person reaches a certain age).  I would not enter non-qualifying expenses (such as income or expenses from a prior tax year or the next tax year). I also wouldn't enter non-qualifying expenses such as mortgage interest that was for non-qualifying purposes. Once I enter the correct amounts, then I let the software do the math for any limitations.