Why can't I attach my 1099-NEC?
If you're filing a joint return with your spouse, double check that the owner of the 1099-NEC is the same as the owner of the Schedule C, Form 4835, or Schedule F that you're trying to attach it to.
For example, if your spouse received a 1099-NEC for a Schedule C business, then the Schedule C business that the 1099-NEC attaches to would also need to be in your spouse's name.