How to File an Amended Business Tax Return

When to File, Where to File, and What Form to Use

Filing an Amended Business Tax Return
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If you've made a mistake on your business tax return, you can file an amended business tax return, but the type of form you file depends on your business type.

If your business is a pass-through type and the tax bill of the business passes through to you on your personal income tax return, you must file an amended personal tax return.

The pass-through business types are the sole proprietorship, limited liability company (LLC), partnership, and S corporation.

Who Needs to File?

You must file an amended business tax return if: 

  • You made a substantial error on your return that will affect your tax liability.
  • You received new information that needs to be included.

You DON'T need to file an amended return if: 

  • Your errors were just math errors—the IRS will make the changes.
  • You forgot to attach tax forms—the IRS will ask for these.

When to File

In general, the IRS says you must file within three years from the date you filed your original return—or with two years from the date you paid the tax, whichever is later.

Filing an amended business tax return should be done as soon as you discover the error. If you must pay more taxes, file the amended return as soon as possible to avoid fines and penalties. If you are due a refund, you have three years from the date you filed your original return to claim it.

What Form to Use

If you need to amend your business tax return, follow the procedure outlined below. Where and how to file an amended return depends on your business type.

Note: For all forms, you must wait until the original return has been filed before you file an amended return. For a credit or refund, you must file within three years (including extensions) after the date you filed your original return or within two years after the date you paid the tax, whichever is later.

Sole Proprietor or Single-Member LLC

File an amended return on Form 1040x by sending the return (you cannot e-file an amended return), including changes to Schedule C and any other schedules, to the appropriate address on Page 4 of the instructions.

Corporation 

File an amended return on Form 1120x by sending the return, along with any schedules that changed, to the address where you filed your original corporate tax return. You can find this address on page 3 of the instructions for Form 1120.

Partnership or Multiple-member LLC

File an amended return on Form 1065 by sending the return, along with any schedules that changed, to the address where the original return was filed. You can find this address on the instructions for Form 1065.

S Corporation

File an amended return on Form 1120s by sending the return, along with any schedules that changed, to the address where the original S corporation tax return was filed. You can find the appropriate address on Page 3 of the instructions for Form 1120s.