Explain what your non-Schedule A deductions on line 3b are, and why they're not definitely related to U.S. source income.
The instructions for Line 3b in the Instructions for Form 1116 are somewhat vague. They state:
Enter on line 3b any other deductions that don't definitely relate to any specific type of income (for example, the deduction for alimony paid from Schedule 1 (Form 1040), line 19a).
However, according to the instructions, lines 3a and 3b are used to report deductions that:
- Aren't shown on line 2, and
- Aren't definitely related to your U.S. source income.
Line 3a is used for certain Schedule A Itemized Deductions, so line 3b would be used for any deductions you claim on your return that are not definitely related to your U.S. source income, and are not among those Schedule A deductions.
The example given is for alimony payments, which would be definitely related to U.S. source income. Similarly, just explain what your non-Schedule A deductions on line 3b are, and why they're not definitely related to U.S. source income.
If you don't know where, on your return, the line 3b deduction is coming from, you may need to go back through your entries in the federal interview to locate the amount. The amount wouldn't be from Schedule A medical expenses, general sales taxes or real estate taxes for your home, since those would be included on line 3a (see the instructions linked above).
