As you know, Forms 1095-C will need to be filed for every employee to whom an ALE (Applicable Large Employer) made an offer of health coverage. Theoretically, Forms 1095-C will be filed in relatively large batches, and each batch will be accompanied by a Form 1094-C Transmittal. Line 19 on Form 1094-C confirms that the submission is the authoritative transmittal for a year. Unless you are submitting Forms 1095-C, there really is no other reason why you would ever file a Form 1094-C.
So what happens if you find that a Form 1095-C has incorrect data and needs to be corrected and resubmitted?
In that case, re-submit only the corrected Form 1095-C (not all the other Forms 1095-C that were originally submitted together), checking the correction box at the top of the form. Along with the corrected Form 1095-C, you would send a nonauthoritative Form 1094-C Transmittal to the IRS in which there would not be an indication on Line 19 of a second authoritative transmittal for the year.