Hi and welcome to Just Answer!For a tax year in which you and your ex-spouse file separate returns, you figure the unused foreign tax or excess limit by using only your own separate income, deductions, taxes, and credits. However, if you file a joint return for any other year involved in figuring a carry back or carryover of unused foreign tax to the current tax year, you will need to make an allocation, as explained in the publication 514 page 23 - http://www.irs.gov/pub/irs-pdf/p514.pdf When you file a joint return in a deduction year, and carry unused foreign tax through that year from the prior year in which you and your spouse filed separate returns, the amount absorbed in the deduction year is the unused foreign tax of each spouse deemed paid or accrued in the deduction year up to the amount of that spouse's excess limit in that year. You cannot reduce either spouse's excess limit in the deduction year by the other's unused foreign taxes in that year.The mechanics of the carry back and carryover, when allocations between husband and wife are needed - if your ex-spouse had no foreign earned income - none of credits will be allocated to her and she would not able to use the credit in following years.
Just so I understand, if my ex-spouse never had foreign earned income, none of the credits can be allocated to her.
If she ever moves to England or any other foreign country and get's foreign earned income, she may never use the credits? Is that correct?
Yes - that is correct.