Is this stated by the CRA in your Notice of Assessment? 

Did you or your spouse attend school full-time for more than 13 weeks in 2024 or 2025? Even if you have a job, the CRA will automatically disqualify you for the CWB if you are a full-time student for more than 3 months, unless you have an eligible dependent child.

Have you checked your bank statements for payments labelled 'ACWB' or 'Canada PRO'? Starting in 2024, the CRA began sending 50% of the CWB in automatic advance payments throughout the year. If they already sent you the money in July, October, and January, they will show $0.00 on your tax return, so you aren't paid twice for the same benefit.

If you are married, is your spouse also claiming the CWB on their return? The CRA only allows one person per household to claim the main benefit. If you both clicked 'Yes' in TurboTax, the CRA system will pick one person to receive it and change the other person's amount to zero.

Does your Notice of Assessment have a specific explanation code at the bottom? Usually, when the CRA makes a change this large, they include a sentence explaining why, such as 'Our records show you are a full-time student' or 'Your spouse has already claimed this benefit.'

Please double-check this information and determine why CRA changed this amount. For more information, call CRA at 1-800-959-8281.

Thank you for choosing TurboTax.

I was not a full time student. My wife did  not claim any CWB. Nothing in my T4 from the employer as well. I did not file or my wife file/claim. We have been filing our own tax cause our claim are all basics and the same for 10 years no change. This was the first time that we encounter this problem in our filing.