Final answer:
Form 941-X is filed alone when claiming a refund or owing additional taxes, used to correct errors on a previously filed Form 941.
Step-by-step explanation:
Form 941-X is filed alone when claiming a refund or owing additional taxes. This is associated with correcting errors on a previously filed Form 941, which employers use to report payroll taxes. The IRS requires employers to use Form 941-X to make corrections to wages, tips, and other compensation; federal income tax withheld; and the employer’s share of Social Security and Medicare taxes that were originally reported on Form 941.
When using Form 941-X, it's not filed with other tax forms such as the W-3 or Form 843. It serves as a stand-alone document to amend previously submitted payroll tax filings. Therefore, the correct answer is D. alone when claiming a refund or owing additional taxes.