How Exact Take Home calculates — and when it refuses to estimate.

Federal withholding

The engine uses the IRS percentage-method structure encoded in versioned data files sourced from IRS Publication 15-T (2026). Federal W-4 fields — Step 2 checkbox, dependents credit, other income, deductions, and extra withholding — are applied in the same order as IRS instructions. Golden tests are anchored to IRS-published worked examples.

FICA taxes

Social Security (6.2%), Medicare (1.45%), and Additional Medicare (0.9% above threshold) use source-backed wage bases, rates, and thresholds from SSA and IRS sources. Every numeric value has a source URL and effective date.

State withholding

Each state uses an explicit archetype strategy: flat rate, progressive brackets, payroll-period table, percentage formula, or no income tax. Supported states calculate normally. Limited states calculate for a documented input scope and report limitations. Blocked states do not calculate — they show an honest explanation instead.

Local taxes

Local calculations use only modeled local rules. The calculator only shows localities that apply to the selected state. Employer-only local taxes are shown as metadata and are not subtracted from employee take-home pay.

Why blocked states fail loudly

Payroll is a high-stakes, YMYL calculation. If official 2026 tables, state-form inputs, or extraction rules are not safely modeled, the app blocks the calculation instead of returning a misleading zero or estimate. Confidence in every shown digit is more important than broad coverage.

Source policy

Every encoded tax value lives in versioned data files with a source URL and effective date. Primary sources — IRS, SSA, state Departments of Revenue, and city/county tax authorities — are the only accepted inputs. Secondary sources may guide research but are never used for numeric values.

Why some states are limited

Limited means the available official source is modeled for a documented input scope, but some W-4 certificate variants, local interactions, or special cases are not yet safe to calculate. Those unsupported combinations are blocked instead of estimated.

ExactTakeHome.com — View state support matrix