NETFILE error code 21: when your access code does not match

What does NETFILE error code 21 mean?

NETFILE error code 21 is an identity check failure: the access code sent with your return is not the code the CRA issued to you. TurboTax Canada's help page describes code 21 this way and tells users to compare the code with their notice of assessment. Code 21 does not appear in the CRA's numbered EFILE list (RC4018 Chapter 2), so the meaning here comes from the software vendor's NETFILE list.

The NETFILE access code is an 8-character code the CRA prints on your notice of assessment so that your next return can be matched to you through information from your last one. It is a convenience for authentication, not a password, and the CRA points you to the code on your most recent notice.

Your return was not filed when code 21 appears. Nothing has been recorded, so correcting the code and sending again does not create a duplicate.

Where do I find my NETFILE access code?

Your NETFILE access code is printed on your most recent notice of assessment, the statement the CRA sends after it processes a return. The CRA's page on completing a return with certified software shows a sample notice with the code marked, and says you can also get it in two other ways.

If you file for the first time, you will not have an access code; the CRA says so directly. Leave the field empty. A first-time filer who sees an identity error should check the first-time filer answer instead, which TurboTax Canada lists as code 32.

How to fix a NETFILE access code error

Fixing a NETFILE access code error takes a few minutes if you check the code character by character before resending.

1. Find your most recent notice of assessment. For a 2025 return filed in the 2026 season, that is normally the notice for your 2024 return.
2. Open the identification or filing section of your software and find the NETFILE access code field.
3. Compare the two codes one character at a time. Look closely at pairs that look alike on screen, such as zero and the letter O, or the digit 1 and the letter I.
4. Remove any spaces before, after or inside the code.
5. If you cannot confirm the code, delete it and leave the field blank.
6. Run the software's review and resend. Save the confirmation number the software shows.

Worked example

Someone filing a 2025 return in April 2026 copies the code from the notice of assessment for their 2023 return because it was the first one in the drawer. The code is valid in format but not the latest one, so the CRA returns code 21. Retyping the code from the 2024 notice, or clearing the field, lets the return go through.

Can I leave the NETFILE access code blank?

Yes. The CRA says entering the access code is not mandatory and that certified software can send your return without it. When the field is empty, the CRA uses other information to confirm your identity instead of details from your last return.

Some programs present the field as if it were required. If yours lets you continue with the field empty, clearing it is the fastest way past a stubborn code 21. If the program will not let you continue, check its help centre or ask its support team how to send without the code.

Where is the UFile NETFILE access code field?

People searching for the UFile NETFILE access code are usually looking for the spot to type or clear it before transmitting. In UFile, as in most certified programs, the code belongs with the filing and identification details rather than with income slips. For product-specific screens and messages, see our page on UFile NETFILE errors.

If Auto-fill my return filled the code for you and code 21 still appears, the imported code may belong to a different tax year's return file. Run Auto-fill again in the correct year's return; our guide to Auto-fill my return not working covers connection problems.

Still rejected after fixing the access code?

If the code is blank or correct and the return is still refused, the identity problem lies elsewhere. The next code you see tells you where.

• Code 31: TurboTax Canada says your personal information does not match what the CRA holds from Service Canada. Check that your name and SIN match your SIN records exactly. See NETFILE error code 31.
• Code N1: authentication failed on name and SIN. TurboTax Canada notes the account locks after five failed attempts, so stop resending after the second failure. See NETFILE error N1.
• Code 84: your spouse or common-law partner's name contains a character the CRA rejects. See NETFILE error code 84.

When you cannot clear an identity error and your details are correct, the CRA says you can print the return and mail it. For the 2025 tax year, NETFILE stays open until January 29, 2027. Our NETFILE error codes list shows every common code and its source.