Form T400A Objection in Canada: Replaced by Form RC592

You received a notice of assessment you disagree with, searched for how to object, and found Form T400A. Before you fill anything in, it helps to know that the form has changed and that a particular form is only one way to start an objection.

This article explains what happened to Form T400A, what a notice of objection needs to contain, where it goes and how the deadlines work. It is general information, and a lawyer or accountant can confirm how it applies to your assessment.

This article covers Canadian federal tax law, which applies in every province.

What happened to Form T400A

CRA's T400A page says the form was cancelled as of 2026-10-26 and replaced with Form RC592, Notice of Objection.

RC592 is a fillable PDF. CRA says it must be downloaded and opened in Acrobat Reader 10 or later, not in a web browser. If you find an older printed or saved copy of T400A, check the current CRA page for RC592 before relying on it.

Do you have to use a form at all?

The Income Tax Act requires a written notice of objection that sets out the reasons for the objection and all relevant facts. CRA's filing options include sending a signed letter by mail or fax to the Chief of Appeals, or delivering it in person. The form CRA now uses for a notice of objection is RC592.

You can also object online. Individuals use My Account for Individuals and businesses use My Business Account, selecting "Register my formal dispute", and you receive a case number. CRA says an objection submitted through a secure portal is assigned to an appeals officer sooner than a paper one.

An authorized representative, such as an accountant, can file for you through Represent a Client by selecting "Register my formal dispute".

What your notice of objection should contain

Whichever route you choose, CRA's guidance lists what the notice should include.

• Your name, complete mailing address and daytime phone number.
• The notice date, the tax year, and your SIN, business number or other account number.
• The relevant facts and your reasons, with copies of supporting documents.
• The representative's name and address, if you have one.
• A signature and date, with an authorized officer signing for a corporation or trust.

If you held back information during an audit or a CRA request and only give it with your objection, the file may be sent back for a second review. It is sensible to gather your supporting documents before you file.

Where to send it and what to expect

A paper objection is served by addressing it to the Chief of Appeals at a CRA District Office or Taxation Centre and delivering or mailing it there. CRA says the Appeals Intake Centre in Sudbury, Ontario receives mailed or faxed objections. You can also deliver it in person.

The RC592 page does not describe the form's sections or a mailing address, so confirm those details on the form itself or with CRA before mailing.

Once CRA receives your objection it gives a case number, which should go in all later correspondence.

Deadlines and what to do next

Individuals (other than trusts) and graduated rate estates have until the later of one year after the filing-due date for the year and 90 days after the notice of assessment was sent. Corporations and most other taxpayers have 90 days. The 90 days run from the day the notice was sent, not the day it was received.

Loss determinations and RRSP or TFSA over-contribution assessments have only a 90-day limit, even for individuals. GST/HST objections follow different rules, with a 90-day deadline and CRA's Form GST159.

• Find the date on your notice of assessment and mark your deadline.
• Confirm that your notice is one that can be objected to; statements of account and auditor's proposal letters cannot.
• Download the current RC592, or choose the online or letter route.
• Gather your supporting documents and sign and date the notice.
• If the deadline has passed, get advice quickly: an extension application must be made within one year after the deadline expired.

Frequently asked questions