--- title: "Understanding System Limitations and \"Blind Spots\" (Year End Tax Packages)" description: Understand the technical limits of T4 generation, worker status locks, and how to handle CRA rejections or amendments with our support team. --- [Skip to content](https://knowledge.corfix.com/articles/payroll-system-limitations-technical-blind-spots#main-content) - [English](https://knowledge.corfix.com/articles/payroll-system-limitations-technical-blind-spots) - [Español](https://knowledge.corfix.com/es/articles/payroll-system-limitations-technical-blind-spots) - [Français](https://knowledge.corfix.com/fr/articles/payroll-system-limitations-technical-blind-spots) - [Português](https://knowledge.corfix.com/pt/articles/payroll-system-limitations-technical-blind-spots) English Show submenu for translations ![black-logo (1)](https://knowledge.corfix.com/hs-fs/hubfs/black-logo%20(1).png?width=300&height=77&name=black-logo%20(1).png) Open main navigation Close main navigation - - [English](https://knowledge.corfix.com/articles/payroll-system-limitations-technical-blind-spots) - [Español](https://knowledge.corfix.com/es/articles/payroll-system-limitations-technical-blind-spots) - [Français](https://knowledge.corfix.com/fr/articles/payroll-system-limitations-technical-blind-spots) - [Português](https://knowledge.corfix.com/pt/articles/payroll-system-limitations-technical-blind-spots) English Show submenu for translations Got a question? 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[Corfix Payroll](https://knowledge.corfix.com/articles/corfix-payroll?hsLang=en) January 9, 2026 # Understanding System Limitations and "Blind Spots" (Year End Tax Packages) ## This article summarizes the technical constraints of the payroll system regarding tax forms and worker status, and how to handle situations that require specialized help. ### ⚠️ Important Warnings - **No "Undo" for Government Filings:** Once a tax form has been sent to the CRA or Revenu Québec, the action cannot be cancelled or recalled. - **System Lockouts:** For your security and tax accuracy, certain changes (like changing a worker's tax category) are locked in the user interface and require technical intervention. #### Overview & Explanation While our system automates the majority of your year-end reporting, there are specific "blind spots"—technical or legal boundaries where the software prevents manual changes to ensure your data remains consistent with government records. In these cases, you won't be able to fix the issue yourself through the standard dashboard and will need to work with our support team for a "back-end" solution. #### How It Works (Technical Constraints) ### 1. Limits on Creating T4s The system generates tax forms based on the payroll cycles you have actually run. - **The Rule:** You cannot create a "manual" T4 in the app for amounts that weren't processed through our payroll system. - **The Fix:** If you need to issue a T4 for income paid outside the system, please contact Support. We must manually inject that data on the back end to ensure your records balance. ### 2. Changing Worker Categories To prevent massive tax errors, the system locks a worker’s classification (e.g., Contractor vs. Employee) once tax data is involved. - **The Rule:** You cannot manually switch a worker's type if it affects their historical tax forms. - **The Fix:** This must be updated by our technical team to ensure the previous year's data is migrated correctly to the new tax category. ### 3. Blocked Workers & Communications If a worker is marked as **"Blocked"** in your settings, the system treats them as inactive for all automated tasks. - **The Rule:** The system will not send emails or electronic T4s to anyone with a "Blocked" status. - **The Fix:** You must provide them with a physical paper copy manually. ### 4. Handling Errors (Reversions and Kickbacks) Once a tax package is generated or submitted, the process becomes more formal. - **The "No Revert" Rule:** You cannot click a button to "reset" a generated T4 to its original state. To fix an error, the current package must be deleted and a new one created. - **CRA Kickbacks:** If the government finds an error (like a wrong Social Insurance Number), they will send a "kickback" or rejection. You must resolve these specific errors before the system will allow you to re-submit. - **Amending Sent Forms:** If you realize a form was wrong *after* it was sent, you cannot "un-send" it. You must process a formal **Amended Return** or a **Cancellation Package** through our support team. #### Use Cases and Benefits - **Audit Protection:** By preventing "on-the-fly" T4 creation, the system ensures your tax forms always match your actual bank transfers and payroll records. - **Communication Control:** The "Blocked" worker rule prevents sensitive tax information from being accidentally sent to terminated or disputed workers. - **Data Integrity:** Requiring back-end help for classification changes ensures your year-end totals remain accurate for both the employer and the employee. - [New in Corfix](https://knowledge.corfix.com/articles/new-in-corfix?hsLang=en) - [Corfix Academy](https://knowledge.corfix.com/articles/corfix-academy?hsLang=en#main-content) - [Field Operations Training](https://knowledge.corfix.com/articles/corfix-academy?hsLang=en#field-operations-training) - [Supervisor & Foreman Training](https://knowledge.corfix.com/articles/corfix-academy?hsLang=en#supervisor-foreman-training) - 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