I added T4A, box 020 to my tax return and it is asking me to add a correct amount to box 022. But I don't know what the amount is? Is it the same as in 020?

According to Canada Revenue Agency (CRA:

Box 022 – Income tax deducted

Enter the total income tax you deducted from the recipient's remuneration during the year. This includes the federal, provincial (except Quebec), and territorial taxes that apply. Leave the box blank if you did not deduct tax.

Do not include an amount you withheld under the authority of a garnishee or a requirement to pay that applies to the employee's previously charged tax arrears.

Box 020 – Self-employed commissions

Enter the amount of commissions you paid to an independent agent. Do not include GST/HST paid to the recipient on those services.

For more information, visit Deducting Income Tax on Pension and Other Income, and Filing the T4A Slip and Summary 

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