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Blog: circular dependencies in benefit microsimulation#681

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blog/tanf-circular-dependency
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Blog: circular dependencies in benefit microsimulation#681
MaxGhenis wants to merge 7 commits intomainfrom
blog/tanf-circular-dependency

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@MaxGhenis MaxGhenis commented Feb 14, 2026

Summary

  • Blog post on circular dependencies in PolicyEngine's benefit computation graph, covering:
    • Housing cycle (FL, AZ, VT): genuine — TANF → housing_cost → rent → housing_assistance → hud_annual_income → TANF. Fixed with pre-subsidy rent.
    • Childcare cycle audit: discovered the 24-state childcare "cycle" was an implementation artifact (CO CCAP placeholder), not a real policy interaction. All TANF states now use accurate post-subsidy childcare_expenses.
    • SALT cycle (AL, IA, LA, MO, MT, OR): genuine — state/federal tax deduction interdependency. Fixed with simplified withholding variables.
    • Other cycles: itemization choice, VA/DE EITC refundability, NY CTC, MD EITC — all genuine, handled via simulation branches.
  • Interactive diagram with Housing and SALT cycle tabs
  • Removed false claims about SNAP↔childcare and SNAP↔electricity cycles

Test plan

  • Blog renders correctly
  • Interactive diagram loads with Housing and SALT tabs
  • All CI checks pass

🤖 Generated with Claude Code

Covers the FL TCA -> housing_cost -> rent -> housing_assistance ->
hud_annual_income -> tanf cycle, with an interactive diagram showing
the dependency chain and how we resolved it using pre-subsidy rent.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Adds detailed coverage of the federal/state tax SALT cycle (6 states
with federal tax deductions + withheld tax simplification), plus a
comprehensive table of 12 cycle-breaking workarounds categorized into
three techniques: pre-subsidy substitution, simplified parallel
variables, and simulation branches.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
AZ TANF has the same cycle as FL TCA - uses housing_cost to
determine shelter status for payment standard reduction.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
- Rewrite childcare section: "The childcare cycle that wasn't" — explains
  the CO CCAP placeholder was the root cause, not a real policy interaction
- Remove false entries from cycles table (SNAP↔childcare, SNAP↔electricity,
  23-state TANF↔childcare)
- Fix MT itemization description
- Update implications section with lesson about auditing statutory
  requirements vs code
- Remove Childcare tab from interactive diagram (now Housing + SALT only)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
@MaxGhenis MaxGhenis changed the title Add blog post on circular dependencies in benefit modeling Blog: circular dependencies in benefit microsimulation Feb 17, 2026
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