If you're a W-2 employee, your employer withholds taxes from every paycheck and sends them to the IRS on your behalf. If you're a 1099 contractor or gig worker, nobody withholds anything for you — which means the IRS expects you to send in roughly the right amount, four times a year, on your own.
Quarterly estimated taxes are pre-payments toward the income tax and self-employment tax you'll owe for the year, due in four installments rather than one lump sum at filing time. Skip them, or pay too little, and you can owe an underpayment penalty even if you pay your full balance by the April deadline — the penalty is for paying late throughout the year, not just for owing money.
Who actually needs to pay
As a rough rule of thumb: if you expect to owe $1,000 or more in tax for the year after subtracting withholding and credits, you're expected to make estimated payments. Almost anyone doing meaningful 1099 or gig income with no other W-2 job withholding enough to cover it falls into this bucket. If you have a day job and gig income on the side, you may be able to cover the gig-income tax by increasing withholding at your day job instead of filing separate quarterly payments — worth asking a preparer about if that applies to you.
Roughly how to estimate what you owe
You don't need to be exact — you need to be close enough to avoid a penalty, then true up at filing time. A workable back-of-envelope approach:
- Total your net income for the quarter: money in, minus legitimate business expenses (mileage, supplies, a portion of your phone bill if used for work, platform fees, etc.).
- Set aside for self-employment tax — this covers the Social Security and Medicare that a W-2 employer would normally split with you. As a 1099 worker, you pay both halves.
- Add your regular income tax rate on top, based on your total expected income for the year (gig income plus anything else).
- A common starting estimate many gig workers use is setting aside roughly a quarter to a third of net income for taxes overall — self-employment tax plus income tax combined — then refining that percentage once you've seen a full year of actual numbers.
This is a starting point, not a substitute for a tax professional, especially in your first year of 1099 income or if your income varies a lot quarter to quarter.
The habit that makes this painless
The hard part of quarterly taxes isn't the math — it's not having the cash on hand when the deadline hits because it was already spent. The fix is treating your tax set-aside like a bill that gets paid the moment income arrives, not something you calculate under deadline pressure. If you're logging income and expenses continuously across every platform or client you work with, you always know roughly what you should have set aside, instead of reconstructing four months of activity the week before a payment is due.
Pay close to what you owe each quarter, keep the set-aside separate from your spending money, and quarterly taxes go from a dreaded surprise to a predictable, boring bill.