Worked examples

Three cases followed line by line from net profit to the federal total, with the quarterly payments and the variations that change the answer most. The figures come from the same engine as the calculators.

• $50,000 of 1099 income

  Self-employment tax dominates; the standard and QBI deductions remove a third of the income before income tax; refundable credits for a parent.

• $75,000 of 1099 income

  Taxable income crosses into the 22% bracket; the marginal cost of an extra dollar of profit; what a maximum SEP-IRA contribution saves.

• $100,000 of 1099 income

  Still below the Social Security wage base; retirement and health insurance deductions at the 22% rate; how close the QBI threshold is.