Schedule SE, QBI, and the quarterly problem.

Self-employment tax is the one that ambushes first-year freelancers. The engine computes it the way the form does, deduction-for-half included.

SE tax, correctly

The 92.35% multiplier, the Social Security wage cap, the deduction for half of SE tax — the actual Schedule SE arithmetic, not a flat 15.3% guess.

Up to 20% of qualified business income comes off before tax, with the phase-outs applied where they apply. The engine runs the real thresholds.

The output you actually need as a freelancer: a defensible per-quarter number, from your income, not a rule of thumb.

Planning estimates. Entity choice and deductions strategy are conversations for your accountant.