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Security and support

Access your tax account and communicate securely with the Ministry of Finance using ONT-TAXS online.

Not an ONT-TAXS online user?

What you need to activate ONT-TAXS online

Prefer to talk to us?

Call the Ministry of Finance at 1-866-ONTTAXS (6688297).

Safe and secure

ONT-TAXS online uses Ontario's secure ONe-key service to protect your tax information. ONe-key verifies your identity, authorizes your access and allows you to securely do business online with the Government of Ontario.

Security starts with you

You play an important role keeping your tax information safe when using ONT-TAXS online. Always remember to:

  • keep your ONe-key ID and password a secret
  • create a unique password and verification questions, and
  • log out of ONT-TAXS online after each session.

Internet browser

To use ONe-key and ONT-TAXS online, your browser must support 128-bit encryption and have JavaScript and cookies enabled.

ONT-TAXS online supports Microsoft Internet Explorer version 10.0 or higher. Other browsers can be used, but they may not display the site as designed or allow you to access all features. Such browsers include:

  • Firefox version 3.5 or higher
  • Safari version 5.0 or higher
  • Chrome version 5.0 or higher
  • Opera version 10 or higher

What browsers work best for online services?

15 minute timeout

To provide enhanced security, if your screen is inactive for more than 15 minutes your ONT-TAXS online session will timeout. When this happens, a Session Expired message will display and you will be prompted to log back into ONe-key and ONT-TAXS online.


View most correspondence issued to your business from the ministry.

View letters

To view letters that have been sent to your business, select View Letters on the Summary page.

Each letter is assigned a unique ID. Select the Letter ID of the letter you wish to view. A new browser window will open and display the letter in a portable document format (PDF). You can print or save it, or close the window and return to ONT-TAXS online.

View and send messages

You can communicate securely with the Ministry of Finance using the Messages feature in ONT-TAXS online. The Messages feature also allows you to attach Word, Excel, PowerPoint, Adobe Acrobat (PDF) and plain text (TXT) files.

Messages at the account level are for that account only. Messages at the main level will display all messages for all accounts. You can send a message to a ministry representative from the Main page or the Account Summary page.

To create messages

  1. Select the account from the drop down list if the message is specific to an account
  2. Select the filing period
  3. Enter a subject line
  4. Compose your message in the yellow-shaded field
  5. If you need to add an attachment, select the Add File button
  6. Select Submit

To view messages, select Messages on the Summary page. Then select the Inbox or Outbox tab. Messages will be listed. Select the message link to view the details.

To view an attachment, select the link for the File Name.

Select Reply to Message to respond. Then, compose your message in the fields provided and select Submit.


Updated: March 07, 2022
Published: March 07, 2022