Andestek S.A. handles administrative and documentary work for small businesses in Buenos Aires — issuing and filing, keeping records in order, and making sure the paperwork a company runs on is correct before somebody else has to read it.
A great many of the problems we are called in to untangle come from one thing: an invoice issued with the wrong letter, to the wrong kind of client. Nobody notices at the time. The client's accountant notices in three months.
A, B, C and M are not formats of the same thing. Each one says something specific about who issued it and what the receiver may do with it, and the tax authority decides which you are allowed to use.
| Letter | Issued by | Issued to | Credit for the buyer |
|---|---|---|---|
| A | A business registered for IVA | Another registered business, or a monotributista | Yes — IVA is shown separately and can be recovered |
| B | A business registered for IVA | Final consumers, exempt entities, monotributistas | No — IVA is inside the price, not itemised |
| C | Monotributistas and exempt taxpayers | Any client at all | No — there is no IVA to itemise |
| M | A registered business the authority has flagged | Registered businesses | Yes, but the buyer must withhold on paying |
The M is the one worth understanding even if it never applies to you. It is issued when the authority sees fiscal risk or insufficient backing on the issuer's side, and it shifts work onto whoever receives it. If an M arrives from a supplier, that is information about the supplier — not a formatting quirk.
To the person issuing it, an invoice is a request for money. To a registered business receiving it, it is also a tax asset or not one — and that difference is real money, which is why the question keeps coming back.
When a registered business receives a factura A, the IVA is itemised and recoverable. When the same purchase arrives on a B or a C, there is nothing to recover: the whole figure is cost. Two suppliers quoting the same number are therefore not quoting the same price to that buyer, and the one who can issue an A is quietly cheaper.
This is not an argument for changing your registration. It is an argument for knowing which conversation you are in — and for saying up front which letter you issue, rather than letting it surface after the work is done.
The document you email is a representation. What makes it an invoice is the CAE — Código de Autorización Electrónico — the number the tax authority grants once the invoice has been validated. The code is what confers fiscal validity, and it can be checked against the authority's own service by anyone holding the document.
This has a practical consequence in both directions. A beautifully formatted file with no valid authorisation code behind it is not an invoice, however convincing it looks. And an invoice you issued and then "corrected" by editing the file is not corrected — the authorised record is the one that counts.
Confirm your client's tax status in writing before issuing the first invoice, and record it with their file. One question at the start removes nearly every problem described above, and it is the single step almost nobody takes.
Andestek S.A. is a private company registered in the City of Buenos Aires, carrying on general business services. Our work is administrative: preparing and filing documents, keeping records complete and in order, organising the paperwork a small business is asked for, and explaining in plain language what a document says and what it does.
Accountancy in Argentina is a registered profession. Where a question is about a tax position, a registration, a category or a filing obligation, the answer comes from a contador público or from the tax authority itself, and we say so rather than filling the gap.
Our registered address in the City of Buenos Aires is used for correspondence and the service of documents. It is not a public office and we do not receive visitors there. Please write or call first.
Tell us in a few lines what needs organising or checking. Written enquiries get a written answer.