W-2 withholding hides a calculation gig income exposes
A traditional W-2 paycheck has federal income tax, state income tax, Social Security, and Medicare automatically withheld before the employee ever sees the money — a process invisible enough that many W-2 employees never think about the underlying tax calculation at all. Side gig and freelance income generally arrives without any of this withholding, exposing a calculation that was previously handled automatically.
Self-employment tax is the piece most commonly underestimated
A W-2 employee's Social Security and Medicare contributions are split between the employee and employer, each paying half. A self-employed person or gig worker is responsible for both halves — the self-employment tax, commonly calculated as 15.3% on approximately 92.35% of net profit — which is a real, substantial tax obligation separate from and in addition to ordinary income tax, and one that's easy to underestimate if you're only thinking in terms of an income tax bracket.
Why net profit, not gross income, is the right starting point
Deductible business expenses — equipment, mileage, a portion of home office costs, supplies — reduce the net profit that both self-employment tax and income tax are calculated against, meaning the real tax owed is based on gross gig income minus legitimate deductible expenses, not the full gross amount received.
Why a concrete set-aside percentage beats a vague habit
"Save some of each gig payment for taxes" is common advice that lacks a specific number to act on — calculating the actual combined self-employment and income tax liability against expected gig income produces a specific percentage that can be set aside from every payment as it's received, converting a vague intention into an executable habit.
Quarterly estimated payments add a timing dimension
Beyond simply setting money aside, gig income above certain thresholds may require quarterly estimated tax payments to the IRS rather than a single payment at annual filing — missing these can result in penalties independent of ultimately paying the full amount owed, making the quarterly breakdown a practically useful additional figure beyond the annual total.
Frequently Asked Questions
A W-2 employer automatically withholds federal income tax, state income tax, Social Security, and Medicare before paying the employee — gig and freelance income generally arrives without this automatic withholding, leaving the full tax calculation and payment responsibility with the earner.
It's the Social Security and Medicare tax obligation that a traditional employer normally splits 50/50 with an employee — a self-employed or gig worker is responsible for both halves, commonly calculated as 15.3% on about 92.35% of net profit, a real cost beyond ordinary income tax.
Deductible business expenses reduce the net profit that both self-employment tax and income tax are actually calculated against — the real tax liability is based on gross income minus legitimate deductible expenses, not the full gross amount received.
A specific percentage can be set aside from every gig payment as it's received, turning the vague common advice to 'save some for taxes' into an executable habit rather than a rough intention with no concrete number attached.
No. All calculation happens locally in your browser — your income, expense, and tax bracket details are never uploaded or logged.