Social security can be taxable income up to 85% depending on your other income streams.
Since you have different type of income, recommend you use TurboTax Tax Calculator per below link:
https://turbotax.intuit.com/tax-tools/calculators/taxcaster/
Or you can use IRS Tax Withholding Estimator to fill out W4 of your part-time job to withhold the bulk of tax payment.
https://apps.irs.gov/app/tax-withholding-estimator
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