Methodology
How BizTax estimates work
Use this page to check the formula, boundary, or route-state rule you care about first. Each section stays focused on one part of the public estimate logic instead of acting like a filing manual.
Each section explains one calculator or boundary rule without pretending to be a filing worksheet.
If a formula, rounding rule, or route-state rule changes, the source bundle and update log should change with it.
How reviewed years and freshness labels work
The active federal calculators currently use reviewed federal packages for 2025 and 2026. The state-cost hub and pilot-state rehearsal pages currently use reviewed 2026 state-fee packages.
The trust bundle currently reflects reviewed source or route-state changes through April 4, 2026. That date is a freshness signal for the current bundle, not a claim that every route models every filing fact.
If a route moves into stale warning, source unavailable, calculation fallback, result-ready-no-provider, under review, or maintenance, the route is expected to show that status before acting more current than the reviewed evidence allows.
Check the trust bundle next
Use these reviewed routes when you want to verify the current source set, see what changed, review disclosure boundaries, or send a correction request.
How BizTax estimates work
BizTax starts with net self-employment income, applies the reviewed 92.35% net-earnings factor, then checks the $400 Schedule SE threshold. Social Security is estimated at 12.4% up to the reviewed wage base of $184,500; Medicare is estimated at 2.9% without that cap.
If filing status crosses the reviewed Additional Medicare threshold, BizTax adds that layer separately and shows the deductible half of self-employment tax. The route does not model optional SE methods, special exemptions, or separate Medicare wages unless those facts are collected.
BizTax starts with an estimated annual federal tax amount, subtracts expected annual withholding, and treats the remainder as the annual gap. It then allocates that gap across four quarterly installments using the reviewed 2026 due dates of April 15, 2026, June 15, 2026, September 15, 2026, and January 15, 2027, reconciling any one-cent rounding remainder inside the installment table.
If prior-year tax and AGI are provided, BizTax also shows a simplified prior-year safe-harbor reference after withholding so readers can compare that path against the current-year installment schedule. It does not replace Form 1040-ES, apply annualized-income installments, or fully model married-filing-separately thresholds unless that status is collected.
This route compares two simplified federal tax treatments. The LLC-style scenario applies the self-employment tax method to full business income; the S-Corp-style scenario applies payroll tax only to the user-entered reasonable salary, split between employer and employee portions.
The route uses reviewed federal payroll assumptions for 2026, but it never calculates or suggests a reasonable salary. It also excludes payroll administration, compliance costs, state-level differences, benefits changes, reasonable-compensation scrutiny, entity-law differences, and QBI interactions.
These pages summarize fixed first-year LLC costs for the five reviewed pilot states. BizTax includes the formation filing fee and the first required reporting fee only when that fee is fixed and known in the reviewed state package.
Variable items such as registered agent pricing, county-dependent publication costs, revenue-based taxes, local licensing, and expedited processing stay in notes instead of the fixed total. Pilot-state data is reviewed quarterly, and stale or under-review datasets show visible warnings before any partner action appears.
The state hub is the main public comparison surface. Individual state pages stay in rehearsal while their source notes, exclusions, and availability signals are checked in a more detailed format.
That split keeps side-by-side comparison on the hub while still letting readers inspect one state's source trail and boundary notes in more detail.
Stale warning
A stale warning means the reviewed source package is still visible, but the year rollover or freshness review is not yet complete. Keep the reviewed year visible and confirm the latest official source before you act.
Source unavailable
Source unavailable means the official source trail is temporarily incomplete, so the visible number stays hidden until the source path can be checked again.
Calculation fallback
Calculation fallback means the page can still explain the rule, but the normal number stays hidden while the estimate logic is being rechecked.
Result ready, no provider
Result ready, no provider means the educational result is visible, but there is no filing or partner path attached to the route. The page stays informational only.
Under review
Under review means the normal result is intentionally hidden while the underlying source or logic package is being checked. The page should explain what is affected and what readers can still verify.
Maintenance
Maintenance means the route is temporarily in rebuild mode. Trust notes stay visible, but the normal number does not return until the rebuild is reviewed.
BizTax keeps intermediate calculations at full precision and rounds displayed amounts to the nearest cent. If visible rows differ from the displayed total by one cent, the rounding-penny rule adjusts the smallest visible row so the displayed sum still matches the displayed total.