Working paper and replication code: how much of the FY2026 U.S. federal deficit traces to the 2025 reconciliation act (P.L. 119-21). Sourced from Treasury, CBO, JCT and BEA data.
#!/usr/bin/env python3
"""FY2026 US federal deficit: how much traces to the 2025 reconciliation act (OBBBA, P.L. 119-21).
Run: python3 fy26_model.py (needs matplotlib for the charts)
Writes: ../results.json, ../charts/*.png, ../inputs_sourced.csv
All dollar figures are $ billions unless stated. Every input carries a source
(publication, table/line). Anything not verified is flagged UNVERIFIED and is either
excluded or exposed as an explicit assumption.
Version 2: tariffs are not an analytical question here. Tariffs, refunds and the economy are
held at actuals; net customs duties are one revenue line inside the residual.
"""
import csv
import json
import os
HERE = os.path.dirname(os.path.abspath(__file__))
OUT = os.path.abspath(os.path.join(HERE, ".."))
os.makedirs(os.path.join(OUT, "charts"), exist_ok=True)
# --------------------------------------------------------------------------
# SOURCES (short keys used in INPUTS)
# --------------------------------------------------------------------------
SRC = {
"MTS": "Treasury, Monthly Treasury Statement Sept 2026 (final FY2026), "
"https://fiscaldata.treasury.gov/static-data/published-reports/mts/MonthlyTreasuryStatement_202609.pdf",
"MBR": "CBO, Monthly Budget Review: September 2026 (Oct 8, 2026), https://www.cbo.gov/publication/61985",
"BASE": "CBO, Budget and Economic Outlook 2026-2036 (Feb 2026) data, Table 1-1, "
"https://www.cbo.gov/system/files/2026-02/51118-2026-02-Budget-Projections.xlsx",
"SCORE": "CBO/JCT, Estimated Budgetary Effects of P.L. 119-21 vs Jan 2025 baseline (Jul 21, 2025), "
"Summary Table + Title VII sheet, https://www.cbo.gov/system/files/2025-07/61570-pl119-21-2025Recon-CLB.xlsx",
"DEBTSVC": "CBO letter to Sen. Merkley (Aug 4, 2025), Table 1 data, "
"https://www.cbo.gov/system/files/2025-08/61466-data.xlsx",
"JCX34": "JCT JCX-34-25 (Jul 1, 2025), revenue effects vs current-policy baseline, total line, "
"https://www.jct.gov/publications/2025/jcx-34-25/",
"OUTLOOK26": "CBO, The Budget and Economic Outlook: 2026 to 2036 (Feb 2026), https://www.cbo.gov/system/files/2026-02/61882-Outlook-2026.pdf",
"JAN25": "CBO, Budget Projections Jan 2025, Table B-1, https://www.cbo.gov/system/files/2025-01/51118-2025-01-Budget-Projections.xlsx",
"CBO62442": "CBO blog, Revenue Collections Through the Individual Income Tax Filing Season (May 21, 2026), https://www.cbo.gov/publication/62442",
"JCX35": "JCT JCX-35-25 (Jul 1, 2025), estimated revenue effects relative to the present-law baseline, NET TOTAL line and footnote [1], "