Resolving Treasury Account Symbols

Every federal budget account has a Federal Account Symbol (FAS) — a stable identifier assigned by the Treasury Department that persists through account renames and reorganizations. The resolve-tas command maps each extracted appropriation provision to its FAS code, enabling cross-bill account tracking regardless of how Congress names the account in different years.

Why TAS Resolution Matters

The same budget account can appear under different names across bills:

Without TAS resolution, these look like different accounts. With it, all three map to FAS code 070-0400 — the same Treasury account.

The FAST Book Reference

The tool ships with fas_reference.json, derived from the Federal Account Symbols and Titles (FAST) Book published by the Bureau of the Fiscal Service at tfx.treasury.gov. This reference contains:

• 2,768 active FAS codes across 156 agencies
• 485 discontinued General Fund accounts from the Changes sheet
• Official titles, agency names, fund types, and legislation references

The FAS code format is {agency_code}-{main_account}:

• 070-0400 → agency 070 (DHS), main account 0400 (Secret Service Ops)
• 021-2020 → agency 021 (Army), main account 2020 (Operation and Maintenance)
• 075-0350 → agency 075 (HHS), main account 0350 (NIH)

Running TAS Resolution

Preview what will happen (no API calls)

congress-approp resolve-tas --dir data --dry-run

This shows how many provisions need resolution per bill and estimates the LLM cost:

  H.R. 2882             448/491  deterministic, 43 need LLM (~$1.29)
  H.R. 4366             467/498  deterministic, 31 need LLM (~$0.93)

Deterministic only (free, no API key)

congress-approp resolve-tas --dir data --no-llm

Matches provisions against the FAST Book using string comparison. Handles ~56% of provisions — those with unique account names or where the agency code disambiguates among multiple candidates. Zero false positives.

Full resolution (deterministic + LLM)

congress-approp resolve-tas --dir data

Provisions that cannot be matched deterministically are sent to Claude Opus in batches, grouped by agency. The LLM receives the provision’s account name, agency, and dollar amount along with all FAS codes for that agency. Each returned FAS code is verified against the FAST Book — if the code is not in the reference, the match is flagged as inferred rather than high.

Achieves ~99.4% resolution across the full dataset.

Resolve a single bill

congress-approp resolve-tas --dir data --bill 118-hr2882

Re-resolve after changes

congress-approp resolve-tas --dir data --bill 118-hr2882 --force

How the Two-Tier Matching Works

Tier 1: Deterministic (free, instant)

For each top-level budget authority appropriation:

1. Direct match: Lowercase the account name, look up in the FAS short-title index. If exactly one FAS code has this title, match it.

2. Short-title match: Extract the first comma-delimited segment of the account name (e.g., “Operation and Maintenance” from “Operation and Maintenance, Army”). Look up in the index. If unique, match.

3. Suffix match: Strip any em-dash agency prefix (e.g., “United States Secret Service—Operations and Support” → “Operations and Support”). Look up the suffix. If unique, match.

4. Agency disambiguation: If multiple FAS codes share the same title (151 agencies have “Salaries and Expenses”), use the provision’s agency to narrow the candidates. If exactly one candidate matches the agency, match it.

5. DOD service branch detection: When the agency is “Department of Defense” but the account name contains “, Army”, “, Navy”, “, Air Force”, etc., the resolver uses the service-specific CGAC code (021, 017, 057) instead of the DOD umbrella code (097).

If none of these strategies produce a single unambiguous match, the provision is left unmatched for the LLM tier.

Tier 2: LLM (requires ANTHROPIC_API_KEY)

Unmatched provisions are batched by agency and sent to Claude Opus with:

• The provision’s account name, agency, and dollar amount
• All FAS codes for that agency from the FAST Book

The LLM returns a FAS code and reasoning for each provision. Each returned code is verified against the FAST Book. Codes confirmed in the reference are marked high confidence; codes the LLM knows from training but that are not in the reference are marked inferred.

Understanding the Output

The command produces tas_mapping.json per bill:

{
  "schema_version": "1.0",
  "bill_identifier": "H.R. 2882",
  "fas_reference_hash": "a1b2c3...",
  "mappings": [
    {
      "provision_index": 0,
      "account_name": "Operations and Support",
      "agency": "United States Secret Service",
      "dollars": 3007982000,
      "fas_code": "070-0400",
      "fas_title": "Operations and Support, United States Secret Service, Homeland Security",
      "confidence": "verified",
      "method": "direct_match"
    }
  ],
  "summary": {
    "total_provisions": 491,
    "deterministic_matched": 448,
    "llm_matched": 39,
    "unmatched": 4,
    "match_rate_pct": 99.2
  }
}

Confidence levels

Match methods

The 40 Unmatched Provisions

Across the full 32-bill dataset, 40 provisions (0.6%) could not be resolved even with the LLM. These are genuine edge cases:

• Postal Service accounts — USPS has its own funding structure
• Intelligence community accounts — classified budget lines
• FDIC Inspector General — FDIC is self-funded
• Newly created programs — not yet in the FAST Book

These 40 provisions represent less than 0.05% of total budget authority.

Updating the FAST Book Reference

The FAST Book is updated periodically by the Bureau of the Fiscal Service. To refresh the bundled reference data:

1. Download the updated Excel from tfx.treasury.gov/reference-books/fast-book
2. Save as tmp/fast_book_part_ii_iii.xlsx
3. Run: python scripts/convert_fast_book.py
4. The updated data/fas_reference.json will be generated
5. Re-run resolve-tas --force to apply the new reference

Cost Summary

This is a one-time cost per bill. Once tas_mapping.json is produced, the FAS codes are permanent — they do not change unless the bill is re-extracted.