Visual-first study tools for all diagnostic tags · tax year 2025 · charts & 3D explorers
Each widget leads with a plain-English “what this does”, then a diagram, meter, waterfall, or Plotly chart — numbers support the picture. Priority tags from the weakness path are marked Priority. New explorers with rotatable 3D views wear 3D chart. These are study tools, not official IRS software — verify year-specific limits against current pubs.
FTF · FTP · interest over months — stacked growth + 3D surface. See which penalty bites first.
Sole prop · partnership · S corp · C corp — stacked tax + 3D income levels. Teaching model.
Formation → default → election flowchart. Links to 3D tax-drag compare.
Guaranteed payment vs distributive share — bar compare.
Step-order basis with path chart, gain & suspended loss.
Money vs property · §731 · before/after basis bars.
§351 sketch + E&P dividend waterfall stack.
Checklist with health meter and clear-vs-flag bars.
Stock vs debt basis dual path + AAA sketch.
Factor score meter and loss implication.
Inventory tanks + COGS waterfall · FIFO/LIFO.
Waterfall + donut · 2025 §179 limits.
Meals / home office bars · QBI limiter compare.
EE vs IC tug-of-war meters · S-corp wage gauge.
Gain character stack · §1245 vs §1231.
Cash vs accrual twin bars · §481(a).
Due-date timeline by entity type.
FTF / FTP / interest explorer with 3D surface.
Who-pays flow · DNI vs distribution bars.
501(c) → UBTI decision path graphic.
SEP / SIMPLE / 401(k) stacked limit bars.
Schedule F bars + SE tax sketch.
Day-split donut · $25k phaseout meter.