You sign back into your turbo tax and you can use the tabs to find what needs to be changed.
You can change information even after paying but before sending it to CRA. Once sent, it's time to do an adjustment.
Please follow the following steps for adding a T4:
1. Click on the t-slips under the Income tab and click on T4
2. Add T4
3. Enter all the information for the T4 slip and click save and continue
4. Then click on done with T4 slips
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