Run the IRS Tax Withholding Estimator if you have a paycheck or pension plus side income
Added
If you have W-2 wages or a pension with tax withholding, the IRS estimator lets you include gig or self-employment income and then generates a pre-filled Form W-4 or W-4P to adjust withholding. It can be a way to cover side-income tax through your paycheck. The IRS suggests checking each January and after major changes like new work or an income change.
The result
Result: IRS: takes about 25 minutes; it doesn't ask for your name, SSN or bank details, and answers aren't saved or shared with the IRS. Correct withholding makes it less likely you'll owe a penalty when you file.
Note: Not tax advice. Rules change and depend on your situation; confirm with the IRS or a tax professional.
Source
IRS (Tax Withholding Estimator) (opens the original source in a new tab). Check it for the latest numbers before you act.