@ar-agents/iibb

Ingresos Brutos (Argentine gross income tax) agent toolkit for the Vercel AI SDK 6+. Pure calculation helpers for retention, perception, and monthly DDJJ assembly across CABA, Provincia de Buenos Aires, and Convenio Multilateral.

pnpm add @ar-agents/iibb

What this package does

• Pure math for retentions, perceptions, and DDJJ assembly. No network, no I/O. Unit-testable.
• Adapter pattern for jurisdictional portals (AGIP, ARBA, Comisión Arbitral). Since v0.2: real AgipPublicAdapter (CABA, no auth) + ArbaCitAdapter (BSAS, host wires CIT-authenticated fetcher). HttpPadronAdapter is the abstract base so hosts can subclass for any DGR.
• Two regimes: LOCAL (single jurisdiction) and CONVENIO MULTILATERAL Article 2 (general regime, distribution by coeficiente unificado).

What this package does NOT do

• Submit DDJJ to a real portal. Each jurisdiction requires fiscal-clave-based authentication; submission is left to the adapter, and the v0.1 adapter stubs throw IibbUnconfiguredError.
• Carry rate-books. Rates change with every annual regulation and per activity (CIIU/NAES). You bring the rate-book; the package does the math.
• Handle CM special regimes (Articles 6-13: construction, transport, professionals, etc.). v0.1 covers Article 2 (general regime) only.
• FX or other-than-ARS currencies. All amounts are ARS centavos integers.

Quick start

import { Experimental_Agent as Agent } from "ai";
import {
  iibbTools,
  RateBook,
  computeDdjj,
  calculateRetention,
} from "@ar-agents/iibb";
import { anthropic } from "@ai-sdk/anthropic";

// Pure: no agent needed.
const result = computeDdjj({
  period: "2026-05",
  regime: "local",
  filerCode: "CABA",
  lines: [
    {
      dateIso: "2026-05-05",
      jurisdiction: "CABA",
      activityCode: "620100", // CIIU/NAES code
      baseImponibleCentavos: 1_000_000, // ARS 10.000
    },
  ],
  rateBook: new RateBook([
    { jurisdiction: "CABA", activityCode: "620100", rate: 0.05 },
  ]),
});

console.log(result.totals.taxDueCentavos); // 50_000 cents (ARS 500)

Wired as agent tools:

const agent = new Agent({
  model: anthropic("claude-sonnet-4-7"),
  tools: iibbTools(), // 4 tools: calc_retention, calc_perception, compute_ddjj, lookup_padron
  system: "Eres un contador asistente para sociedades-IA argentinas.",
});

Convenio Multilateral example

const result = computeDdjj({
  period: "2026-05",
  regime: "cm",
  filerCode: "CM",
  rateBook,
  cmCoefficients: { CABA: 0.6, BSAS: 0.4 }, // sums to 1.0
  lines: [...],
});
// result.byJurisdiction → [{ jurisdiction: "CABA", ... }, { jurisdiction: "BSAS", ... }]
// result.cmCoefficients echoes back the input.

Padrón lookup

CABA — no auth needed:

import { iibbTools, AgipPublicAdapter } from "@ar-agents/iibb";

const tools = iibbTools({
  adapters: { CABA: new AgipPublicAdapter() },
});

const status = await tools.iibb_lookup_padron.execute({
  cuit: "20417581015",
  jurisdiction: "CABA",
});
// → { cuit: "...", jurisdiction: "CABA", inscribed: true, regime: "local" } | null

BSAS — host wires a CIT-authenticated fetcher:

import { ArbaCitAdapter } from "@ar-agents/iibb";

const authedFetch = async (url, init) =>
  fetch(url, { ...init, headers: { ...init?.headers, cookie: `JSESSIONID=${process.env.ARBA_CIT_SESSION}` } });

const tools = iibbTools({
  adapters: { BSAS: new ArbaCitAdapter({ fetch: authedFetch }) },
});

Any other DGR — subclass HttpPadronAdapter:

import { HttpPadronAdapter, type JurisdictionCode, type Padron } from "@ar-agents/iibb";

class DgrSantaFeAdapter extends HttpPadronAdapter {
  readonly jurisdiction: JurisdictionCode = "SF";
  protected buildLookupRequest(cuit: string) {
    return { url: `https://api.santafe.gov.ar/iibb/padron/${cuit}` };
  }
  protected parseLookupResponse(text: string, cuit: string): Padron | null {
    const j = JSON.parse(text);
    return j.activo ? { cuit, jurisdiction: "SF", inscribed: true, regime: "local" } : null;
  }
}

Errors

import {
  IibbError,
  IibbUnconfiguredError, // adapter not wired
  IibbValidationError,   // bad input (bad period, mismatched jurisdiction, etc.)
  IibbRateNotFoundError, // rate-book missing an (jurisdiction, activityCode) entry
} from "@ar-agents/iibb";

Constraints (quick reference)

• Centavos for all amounts (ARS integers). No floats.
• Rates are fractions (0.035 = 3.5%). Never percentages.
• Period is YYYY-MM. The validator rejects anything else.
• CM coefficients sum to 1.0 ±0.001 tolerance.

For LLM agents using these tools, see AGENTS.md.

License

MIT — Nazareno Clemente [email protected]