Tax Research
The studies behind the engine: how each tricky rule is modeled, computed, and verified against official sources. No fluff — methodology you can audit.
How Pennsylvania's local Earned Income Tax is resolved at the Political Subdivision level — resident vs. workplace rates, DCED triggers, and the maximum-rate rule, with reference tables.
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The complete rulebook: every data source (IRS Pub 15-T, SSA, state DORs), every computation step, and every edge case the calculator applies — W-4 Step 2(c), FLSA blended overtime, FICA convergence, and more.
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More studies are in the pipeline, each published only after verification against official sources. Suggest a topic any time.