@tbleaney If your income exceeds the OAS clawback threshold level, the amount of the clawback will be deducted on line 23500 (line 235 prior to 2019) social benefits repayment. This reduces your taxable income so that you are not taxed on the clawback amount being paid back.
The clawback will also be shown on line 42200 (line 422 prior to 2019) social benefits repayment, which adds the amount to your total payable.
We suggest you to contact CRA for more details about the clawback, as it's a specific calculation.
Here is the link to contact CRA
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