CWU: No. The IRS requires you to mail a 940 amended return.
Prepare an amended Form 940 on the same form you originally filed and now intend to amend. (Employees > 94x Forms > 940, or On the Fly Forms > 94x Forms On the Fly > 940). Follow the Form 940 instructions to complete the form, and check Amended under Type of Return on the data entry screen.
From Instructions for Form 940:
"Can You Amend a Return?
You use the 2017 Form 940 to amend a return that you previously filed for 2017. If you are amending a return for a previous year, use the previous year's Form 940.
Follow the steps below to amend your return.
- Use a paper return to amend a Form 940 filed under an electronic filing program.
- Check the amended return box in the top right corner of Form 940, page 1, box a.
- Fill in all the amounts that should have been on the original form.
- Sign the form.
- Attach an explanation of why you are amending your return. For example, tell us if you are filing to claim credit for tax paid to your state unemployment fund after the due date of Form 940.
- File the amended return using the Without a payment address (even if a payment is included) under Where Do You File.
- If you file an amended return for an aggregate Form 940, be sure to attach Schedule R (Form 940). Complete Schedule R (Form 940) only for employers who have adjustments on the amended Form 940.
Where Do You File?
Where you file depends on whether you include a payment (check or money order) with your return. However, mail your amended return to the Without a payment address even if a payment is included."