Low-Level WSFE and WSMTXCA Service Access

The exact layer gives you direct access to the raw ARCA service methods via arca.wsfe and arca.wsmtxca. Where the high-level issue() facade automatically derives the voucher type, reserves the next number, and handles indeterminate recovery, the exact layer keeps all of that control in your hands — you own the voucher number, you construct the full request, and you receive the raw fiscal evidence as returned by ARCA.

Direct calls to arca.wsfe.issue() and arca.wsmtxca.issue() bypass the SDK’s automatic idempotency and indeterminate-recovery logic. Use the facade (arca.issue()) for production invoice issuance unless you need the exact layer’s additional control. If you do use it, your application is responsible for durably reserving the voucher number, handling indeterminate outcomes, and ensuring you never retry a potentially successful authorization.

When to Use the Exact Layer

Use arca.wsfe or arca.wsmtxca directly when:

You need a service-level method the facade does not expose, such as getLastAuthorizedVoucher or getServerStatus.
You need to issue a voucher in a currency, with a receiver, or with fiscal fields the issue() facade does not support.
Your application owns its own voucher number sequence and you cannot let the SDK call getNextVoucherNumber automatically.
You want to read ARCA’s runtime reference catalogs (voucher types, VAT rates, currencies) rather than using static constants.
You are building a custom workflow — for example, constructing the request in one step and authorizing it in another.

Builders

Before calling arca.wsfe.issue(), use a builder to construct the WsfeVoucherInput. Builders handle all fiscal arithmetic — net amounts, VAT, rounding — so you do not need to compute them manually.

`buildFacturaB(input)`

Derives a complete WsfeVoucherInput for a Factura B. Accepts integer minor units (centavos) as taxableAmount and performs VAT calculation using Round Half Even, matching ARCA’s documented rounding criterion.

import { buildFacturaB, createArcaClient } from "facturas";
import {
  ARCA_CONCEPT_TYPES,
  ARCA_DOCUMENT_TYPES,
  ARCA_RECEIVER_VAT_CONDITIONS,
} from "facturas/constants";

const arca = createArcaClient({
  taxId: "20123456786",
  certificatePem: process.env.ARCA_CERTIFICATE_PEM!,
  privateKeyPem: process.env.ARCA_PRIVATE_KEY_PEM!,
  environment: "test",
});

const data = buildFacturaB({
  salesPoint: 1,
  concept: ARCA_CONCEPT_TYPES.PRODUCTOS,
  documentType: ARCA_DOCUMENT_TYPES.CONSUMIDOR_FINAL,
  documentNumber: 0,
  receiverVatConditionId: ARCA_RECEIVER_VAT_CONDITIONS.CONSUMIDOR_FINAL,
  voucherDate: "2026-09-02",
  taxableAmount: 10_000, // ARS 100.00 in minor units (centavos)
  vatRate: 21,
});

BuildFacturaB input fields

number

required

Sales point number.

number

required

Concept type code. Use ARCA_CONCEPT_TYPES.

number

required

Receiver document type code. Use ARCA_DOCUMENT_TYPES.

number

required

Receiver document number. Pass 0 for consumidor final.

number

required

Receiver VAT condition code. Use ARCA_RECEIVER_VAT_CONDITIONS.

string

required

Invoice date. Accepts YYYY-MM-DD or YYYYMMDD.

number

required

Taxable base amount in minor units (centavos). Must be a positive integer. When vatRate is positive, the amount must produce at least one centavo of VAT after rounding.

number

required

VAT rate as a percentage (0, 2.5, 5, 10.5, 21, or 27).

"ARS" | "USD"

default:"\"ARS\""

ISO currency code. The builder maps this to the ARCA currency ID internally.

string

Exchange rate as a decimal string. Required when currency is not "ARS".

To issue in USD, pass the exchange rate as a decimal string:

import { buildFacturaB } from "facturas";
import {
  ARCA_CONCEPT_TYPES,
  ARCA_DOCUMENT_TYPES,
  ARCA_RECEIVER_VAT_CONDITIONS,
} from "facturas/constants";
// ---cut---
const usdData = buildFacturaB({
  salesPoint: 1,
  concept: ARCA_CONCEPT_TYPES.PRODUCTOS,
  documentType: ARCA_DOCUMENT_TYPES.CONSUMIDOR_FINAL,
  documentNumber: 0,
  receiverVatConditionId: ARCA_RECEIVER_VAT_CONDITIONS.CONSUMIDOR_FINAL,
  voucherDate: "2026-09-02",
  taxableAmount: 10_000, // USD 100.00 in minor units
  vatRate: 21,
  currency: "USD",
  exchangeRate: "1095.500000",
});

`buildFacturaC(input)`

Same pattern as buildFacturaB, but constructs a Factura C with zero VAT. Accepts the same currency and exchange rate options.

`arca.wsfe` — WSFE Service

Issuance

`wsfe.issue({ voucherNumber, data })`

Sends a single WSFE FECAESolicitar request for the exact voucher number you supply. Returns a typed outcome: authorized, rejected, or indeterminate.

import { buildFacturaB, createArcaClient } from "facturas";
import { ARCA_CONCEPT_TYPES, ARCA_DOCUMENT_TYPES, ARCA_RECEIVER_VAT_CONDITIONS } from "facturas/constants";
const arca = createArcaClient({ taxId: "20123456786", certificatePem: "", privateKeyPem: "", environment: "test" });
const data = buildFacturaB({ salesPoint: 1, concept: ARCA_CONCEPT_TYPES.PRODUCTOS, documentType: ARCA_DOCUMENT_TYPES.CONSUMIDOR_FINAL, documentNumber: 0, receiverVatConditionId: ARCA_RECEIVER_VAT_CONDITIONS.CONSUMIDOR_FINAL, voucherDate: "2026-09-02", taxableAmount: 10_000, vatRate: 21 });
// ---cut---
// 1. Reserve the number durably in your own store.
const voucherNumber = await arca.wsfe.getNextVoucherNumber({
  salesPoint: data.salesPoint,
  voucherType: data.voucherType,
});

// 2. Issue exactly once.
const issued = await arca.wsfe.issue({ voucherNumber, data });

if (issued.kind === "authorized") {
  console.log(issued.cae, issued.caeExpiry, issued.voucherNumber);
} else if (issued.kind === "rejected") {
  console.error(issued.errors, issued.observations);
} else {
  // indeterminate — consult the same number before any new attempt
  const lookup = await arca.wsfe.lookupVoucher({
    number: voucherNumber,
    salesPoint: data.salesPoint,
    voucherType: data.voucherType,
  });
  console.log(lookup.kind);
}

wsfe.issue() always makes exactly one transport attempt, regardless of the client’s retries setting. It never refreshes credentials automatically and never retries on an indeterminate outcome. This prevents a potentially successful authorization from being silently duplicated.

Indeterminate outcomes can arise from timeouts, connection failures, invalid SOAP responses, or incomplete/contradictory results from ARCA. An explicit authentication rejection from ARCA comes back as reason: "authentication_rejected" with typed evidence in the authentication field.

Voucher Queries

`wsfe.getNextVoucherNumber({ salesPoint, voucherType })`

Returns the next voucher number to use for the given sales point and voucher type. Call this immediately before authorizing if your number sequence may have moved since your last call.

import { createArcaClient } from "facturas";
const arca = createArcaClient({ taxId: "20123456786", certificatePem: "", privateKeyPem: "", environment: "test" });
// ---cut---
const next = await arca.wsfe.getNextVoucherNumber({ salesPoint: 1, voucherType: 6 });
console.log(next); // number

`wsfe.lookupVoucher({ number, salesPoint, voucherType })`

Looks up a voucher at ARCA by coordinates. Returns the voucher summary or not_found (WSFE code 602). Use this after an indeterminate wsfe.issue() outcome to check whether the authorization actually went through.

`wsfe.getVoucherInfo({ number, salesPoint, voucherType })`

Returns full voucher detail from ARCA, or null if not found.

`wsfe.getSalesPoints(input?)`

Returns the list of sales points configured for the authenticated CUIT on WSFE. Accepts an optional { representedTaxId, forceRefresh } input object. Returns an empty list when no sales points are registered for web services (WSFE code 602).

Runtime Catalogs

These methods return live data from ARCA and are useful when the static constants in facturas/constants are not sufficient.

import { createArcaClient } from "facturas";
const arca = createArcaClient({ taxId: "20123456786", certificatePem: "", privateKeyPem: "", environment: "test" });
// ---cut---
const voucherTypes  = await arca.wsfe.getVoucherTypes();
const documentTypes = await arca.wsfe.getDocumentTypes();
const currencies    = await arca.wsfe.getCurrencyTypes(); // returns ARCA IDs, not ISO codes
const vatRates      = await arca.wsfe.getVatRates();

All authenticated catalog methods accept forceRefresh: true to discard the cached WSAA ticket and request a fresh Token Authorization before the call. Pass this option when you know a ticket has expired or been invalidated externally.

`wsfe.getServerStatus()`

Checks the WSFE backend health. Returns a status object from ARCA. Useful for health checks and operational dashboards.

`arca.wsmtxca` — WSMTXCA Service

WSMTXCA follows the same pattern as WSFE but adds full line-item encoding. Use it when your invoices require itemized breakdowns at the ARCA service level. The facade also routes to WSMTXCA when you pass { service: "wsmtxca" } to arca.issue(). The exact layer is available for cases where you need to build the WsmtxcaIssueRequest yourself.

Methods

`wsmtxca.issue({ data })`

Issues a WSMTXCA voucher from a fully constructed WsmtxcaIssueRequest. Same outcome semantics as wsfe.issue() — one transport attempt, no automatic retries, typed indeterminate result.

`wsmtxca.getLastAuthorizedVoucher({ voucherType, salesPoint })`

Returns the last authorized voucher number. When no voucher has been issued for the given coordinates, WSMTXCA code 1502 returns 0.

`wsmtxca.getVoucher({ voucherType, salesPoint, voucherNumber })`

Returns full voucher detail. Returns not_found on WSMTXCA code 1503.

`wsmtxca.lookupVoucher({ voucherType, salesPoint, voucherNumber })`

Looks up a voucher at ARCA by coordinates. Returns the voucher summary or not_found on WSMTXCA code 1503. Use this after an indeterminate wsmtxca.issue() outcome to verify whether the authorization succeeded.

`wsmtxca.getSalesPoints(input?)`

Returns the sales points registered for the authenticated CUIT on WSMTXCA. Accepts an optional { representedTaxId, forceRefresh } input object.

All authenticated WSMTXCA methods accept forceRefresh: true to renew the WSMTXCA WSAA ticket before the call.

`WsfeVoucherInput` — Full Escape Hatch

When you need fiscal fields the facade and builders do not expose — exemptions, untaxed amounts, multiple VAT rates, or custom totals — construct a WsfeVoucherInput directly. Amounts use decimal values in major units (e.g., 100.00 for ARS 100); the SDK validates them locally and serializes them as canonical two-decimal strings before sending to ARCA.

import type { WsfeVoucherInput } from "facturas/wsfe";
import {
  ARCA_CONCEPT_TYPES,
  ARCA_CURRENCY_IDS,
  ARCA_DOCUMENT_TYPES,
  ARCA_RECEIVER_VAT_CONDITIONS,
  ARCA_VAT_RATES,
  ARCA_VOUCHER_TYPES,
} from "facturas/constants";

const exactData: WsfeVoucherInput = {
  salesPoint: 1,
  voucherType: ARCA_VOUCHER_TYPES.FACTURA_B,
  concept: ARCA_CONCEPT_TYPES.PRODUCTOS,
  documentType: ARCA_DOCUMENT_TYPES.CONSUMIDOR_FINAL,
  documentNumber: 0,
  receiverVatConditionId: ARCA_RECEIVER_VAT_CONDITIONS.CONSUMIDOR_FINAL,
  voucherDate: "2026-09-02",
  totalAmount: 121,
  nonTaxableAmount: 0,
  netAmount: 100,
  exemptAmount: 0,
  taxAmount: 0,
  vatAmount: 21,
  currencyId: ARCA_CURRENCY_IDS.ARS,
  exchangeRate: "1",
  vatRates: [{ id: ARCA_VAT_RATES.IVA_21, baseAmount: 100, amount: 21 }],
};

WsfeVoucherInput uses ARCA protocol identifiers: currencyId is "PES" or "DOL", and vatRates[].id uses ARCA’s internal codes (e.g., 5 for 21%). The high-level facade and builders accept ISO currency codes and percentage values and translate them for you.

Absence and Not-Found Semantics

Exact-layer absence handling varies by operation and service:

Not-found codes by operation

Operation	Code	Result
WSFE `FECompConsultar`	602	`not_found`
WSFE `FEParamGetPtosVenta`	602	Empty list (no sales points for web services)
WSMTXCA `consultarComprobante`	1503	`not_found`
WSMTXCA `consultarUltimoComprobanteAutorizado`	1502	Voucher number `0`

Note: WSMTXCA code 602 is not an absence indicator — it remains an error.

Authentication Retry Behavior

Catalog and query operations (read-only methods) may retry once with a forced credential refresh after an explicit, typed ArcaAuthenticationError. Issuance operations (wsfe.issue(), wsmtxca.issue()) never refresh credentials or retry automatically — any form of uncertainty results in an indeterminate outcome, not a retry. Pass forceRefresh: true to any authenticated method to disable automatic authentication recovery for that call and force a fresh WSAA ticket request unconditionally.

Get Started

Core Concepts

Guides

CLI

Reference

Low-Level WSFE and WSMTXCA Service Access

When to Use the Exact Layer

Builders

`buildFacturaB(input)`

`buildFacturaC(input)`

`arca.wsfe` — WSFE Service

Issuance

`wsfe.issue({ voucherNumber, data })`

Voucher Queries

`wsfe.getNextVoucherNumber({ salesPoint, voucherType })`

`wsfe.lookupVoucher({ number, salesPoint, voucherType })`

`wsfe.getVoucherInfo({ number, salesPoint, voucherType })`

`wsfe.getSalesPoints(input?)`

Runtime Catalogs

`wsfe.getServerStatus()`

`arca.wsmtxca` — WSMTXCA Service

Methods

`wsmtxca.issue({ data })`

`wsmtxca.getLastAuthorizedVoucher({ voucherType, salesPoint })`

`wsmtxca.getVoucher({ voucherType, salesPoint, voucherNumber })`

`wsmtxca.lookupVoucher({ voucherType, salesPoint, voucherNumber })`

`wsmtxca.getSalesPoints(input?)`

`WsfeVoucherInput` — Full Escape Hatch

Absence and Not-Found Semantics

Authentication Retry Behavior

​When to Use the Exact Layer

​Builders

​buildFacturaB(input)

​buildFacturaC(input)

​arca.wsfe — WSFE Service

​Issuance

​wsfe.issue({ voucherNumber, data })

​Voucher Queries

​wsfe.getNextVoucherNumber({ salesPoint, voucherType })

​wsfe.lookupVoucher({ number, salesPoint, voucherType })

​wsfe.getVoucherInfo({ number, salesPoint, voucherType })

​wsfe.getSalesPoints(input?)

​Runtime Catalogs

​wsfe.getServerStatus()

​arca.wsmtxca — WSMTXCA Service

​Methods

​wsmtxca.issue({ data })

​wsmtxca.getLastAuthorizedVoucher({ voucherType, salesPoint })

​wsmtxca.getVoucher({ voucherType, salesPoint, voucherNumber })

​wsmtxca.lookupVoucher({ voucherType, salesPoint, voucherNumber })

​wsmtxca.getSalesPoints(input?)

​WsfeVoucherInput — Full Escape Hatch

​Absence and Not-Found Semantics

​Authentication Retry Behavior

When to Use the Exact Layer

Builders

`buildFacturaB(input)`

`buildFacturaC(input)`

`arca.wsfe` — WSFE Service

Issuance

`wsfe.issue({ voucherNumber, data })`

Voucher Queries

`wsfe.getNextVoucherNumber({ salesPoint, voucherType })`

`wsfe.lookupVoucher({ number, salesPoint, voucherType })`

`wsfe.getVoucherInfo({ number, salesPoint, voucherType })`

`wsfe.getSalesPoints(input?)`

Runtime Catalogs

`wsfe.getServerStatus()`

`arca.wsmtxca` — WSMTXCA Service

Methods

`wsmtxca.issue({ data })`

`wsmtxca.getLastAuthorizedVoucher({ voucherType, salesPoint })`

`wsmtxca.getVoucher({ voucherType, salesPoint, voucherNumber })`

`wsmtxca.lookupVoucher({ voucherType, salesPoint, voucherNumber })`

`wsmtxca.getSalesPoints(input?)`

`WsfeVoucherInput` — Full Escape Hatch

Absence and Not-Found Semantics

Authentication Retry Behavior