What is the Convenio Multilateral and when do I need it?

Last verified: 27 Oct 2026 · Status: Changing

Short answer. The Convenio Multilateral of 18 August 1977 is the agreement among Argentina's provinces and the City of Buenos Aires that splits one business's gross income tax (IIBB) base among them. You need it once you operate, sell or incur expenses in two or more jurisdictions. Generally 50% of income follows expenses and 50% follows sales.

As of 26 Oct 2026. Rules in force at that date.

Key rules

What it is. The Convenio Multilateral del 18/08/77 (CM) covers one taxpayer's activity in two or more jurisdictions whose income comes from a single, economically inseparable process (CM art. 1). Each jurisdiction taxes only its share, at its own rates (CM art. 28); municipalities too (CM art. 35).

When you need it. CM art. 1 covers manufacturing in one jurisdiction and selling in another, management separate from operations, a main seat in one jurisdiction with sales or purchases in others, and services to people or assets elsewhere. Its last paragraph catches most businesses: expenses of any kind linked to activity in more than one jurisdiction, even non computable ones, bring you inside the CM, however the deal is closed.

Online sales. Sales through any electronic medium or platform fall under that paragraph (RG CA 5/2021 art. 1), with nexus where the buyer lives if you have a "digital presence" there, such as selling online to buyers there or using local payment processors (arts. 2 and 3).

How the base is split (general regime). 50% in proportion to expenses actually borne in each jurisdiction and 50% in proportion to income from each jurisdiction (CM art. 2). Income from remote sales goes to the buyer's domicile (CM art. 2(b)); for goods, that means the place of final destination (RG CA 14/2017 art. 1(a)). Figures come from the last balance closed in the previous calendar year (CM art. 5).

Who runs it. A Comisión Plenaria and a Comisión Arbitral seated in the City of Buenos Aires (CM arts. 15 and 19), which issues binding interpretive rules and decides specific cases (CM art. 24).

How you comply. Register through the RUT Padrón Federal with your CUIT and ARCA fiscal password (RG CA 5/2019 art. 5). All 24 jurisdictions use it since 1 August 2026 (Padrón Federal page, RG CA 9/2026). File monthly returns (CM03, or CM04 in some cases) and the annual CM05 in SIFERE WEB (RG CA 16/2016 art. 1).

What changes the answer

Your sector. Construction (10/90), professionals and intermediaries (80/20), transport, insurers and banks use special rules (CM arts. 6 to 12).
Starting or ceasing in a jurisdiction. A new jurisdiction taxes all income earned there until a closed balance includes it (CM art. 14(a)); on ceasing, new coefficients apply from the next month (CM art. 14(b)).
Exports. Export income and related expenses are left out of the coefficient (RG CA 2/2018 art. 1).
Offline sales with no expense in the buyer's province. For online sales RG CA 5/2021 settles nexus through digital presence. For other remote sales with no expense at the buyer's end, whether that province gets a share is fact dependent and the sources reviewed do not settle it.

Worked examples

Facts. An SRL sells goods online (CABA NAES 479101; PBA class 4791) from a warehouse in the City of Buenos Aires (CABA) to buyers there and in Buenos Aires Province (PBA). Its 2025 balance shows total income of ARS 2,000,000,000: 40% to CABA buyers, 60% to PBA buyers. Computable expenses: 80% CABA, 20% PBA. October 2026 sales: ARS 100,000,000 net of VAT. Pesos converted at dólar MEP ARS 1,563.90 per US$ on 23 Oct 2026, a rate supplied by some secondary summaries (unconfirmed) (see /data/mep/).

Step or item	Time	Cost ARS	Cost USD
Register in the CM via Padrón Federal	Online; up to 20 days provisional (RG CA 5/2019 art. 6)	No fee in sources (unconfirmed)	n/a
CABA base, 0.60 × 100,000,000	Monthly	60,000,000	38,365.62
PBA base, 0.40 × 100,000,000	Monthly	40,000,000	25,577.08
CABA tax at 5.00%	Due 17 to 20 Nov 2026	3,000,000	1,918.28
PBA tax at 5%	Due 17 to 20 Nov 2026	2,000,000	1,278.85
Total October IIBB		5,000,000	3,197.14

Step 1. CM needed? Yes: PBA sales plus PBA expenses (CM art. 1) and digital presence (RG CA 5/2021).

Step 2. Coefficients (CM arts. 2 and 5). CABA: (0.40 + 0.80) ÷ 2 = 0.60. PBA: (0.60 + 0.20) ÷ 2 = 0.40. So ARS 60,000,000 to the CABA and ARS 40,000,000 to the PBA.

Step 3. Rates. * CABA: 5.00% above ARS 391,128,000 of prior year income (CABA Law 6927 Annex art. 5, replaced by Law 6948 art. 2). Whether a CM taxpayer measures this on total or CABA income is unstated (unconfirmed); both exceed it here. * PBA: 5% general column; reduced brackets need prior year income, inside and outside the province, of ARS 1,834,326,000 or less (PBA Law 15.558 art. 20). ARS 2,000,000,000 exceeds it.

**Step 4) art. 3).

Why it matters. Without the CM, each jurisdiction could claim tax on the full ARS 100,000,000: ARS 10,000,000 (US$6,394.27) on the same sales. The CABA warehouse pulls 60% of the base to the CABA although only 40% of sales go there.

Cost to do it: no fee or capital found in the sources (unconfirmed); up to 20 days to confirm registration; then monthly CM03 and annual CM05 (2025 return due 30 June 2026, RG CA 20/2025 art. 2).

Practical traps

Staying local after you expand. A local registration does not cover sales into other provinces once art. 1 applies, and every province can audit you directly (CM art. 29).
Using this year's figures. The coefficient uses last year's balance (CM art. 5). If it is not ready, January to March use last year's coefficient and April adjusts (RG CA 10/2019 art. 2).
Counting goods and advertising as expenses. Cost of goods, advertising, taxes, interest and director fees above 1% of accounting profit are excluded (CM art. 3).

FAQ

Does the CM lower my tax? Not by itself. It stops two jurisdictions taxing the same income; rates still differ.

Who settles disputes? The Comisión Arbitral decides specific cases (CM art. 24(b)). Its rulings can be appealed to the Comisión Plenaria within 30 business days (CM art. 25).

Is the text changing? Amendments to CM arts. 16, 18, 19 and 31 (Comisión Plenaria Res. 15/24 and 23/24) apply only once every jurisdiction approves them (CABA Law 6926 arts. 7 to 9); status (unconfirmed).

Published 27 Oct 2026 from our research draft. Points marked (unconfirmed) have not yet been checked against the official text; rely on the primary sources linked below.