I'm a W-2 employee with a side gig — do I need to pay estimated taxes?

Probably yes, because your side income usually has no withholding, so taxes pile up until you settle them. The IRS expects taxes paid as you earn, generally requiring quarterly estimated payments if you'll owe $1,000 or more beyond what's withheld. You have two options: send quarterly estimates (due roughly April, June, September, and January) on Form 1040-ES, or — often simpler — bump up the withholding on your W-2 job by submitting a new W-4 with extra dollars on line 4(c). The withholding trick is powerful because withholding is treated as paid evenly across the year, sidestepping quarterly deadlines. Set aside roughly 25–35% of side income depending on your bracket and self-employment tax. Estimate the combined bite at wealthserene.com/tools/self-employed-hub.