The short version: a W-2 has tax taken out along the way. A 1099 has nothing taken out — the money arrives whole, and the tax is still owed. That is the whole surprise, and it is why people who did well all year get a bill in April.
Two taxes, not one
Income tax applies as usual. On top of it sits self-employment tax — 15.3% covering Social Security and Medicare. An employee splits that with their employer; working for yourself, you are both halves. It kicks in at $400 of net earnings.
Because nobody is withholding, the IRS expects the money in instalments through the year rather than all at once in April. Those are estimated payments, and getting them roughly right is most of what keeps April calm.
You are taxed on profit, not on what landed in the account
Ordinary and necessary business expenses come off first. The ones people most often forget:
- Mileage — the IRS sets a standard rate each year, but only if you kept a log
- The business share of your phone and internet
- Tools, supplies, software subscriptions, bank and card-processing fees
- A home office, if the space is used regularly and only for work
- Health insurance premiums you pay yourself
- Half of your self-employment tax, deducted before your income is even counted
Keep the receipts and run the money through a separate account. It is the difference between claiming what you are owed and guessing.