If you’re an independent contractor or a small business owner and made an error on Form T2125 (Statement of Business or Professional Activities), you can amend your return online. The Canada Revenue Agency must have already accepted the return, and you must have filed it in the last 10 years. Just log into My Account and select “change my return” to initiate changes. If you prefer to request a change via the post, use Form T1-ADJ (T1 Adjustment request) or send a letter with the details of your request and documents supporting the request.Unfortunately, there is no form to request changes to a corporate tax return. Instead, you should write a letter to your local tax centre. Include the name of your corporation, the Business Number, the tax year, and a summary of the changes. Also, include financial documents to back up your claims and copies of any schedules that need to be modified.After processing your request, the CRA will either issue a reassessment showing which changes were accepted or a letter explaining why your changes were rejected. If you’ve forgotten to report income, claim a deduction, or include other information on your return, you can start this process as soon as the CRA assesses your original return. In most cases, the process to amend a business tax return is pretty straightforward.