Written for Mexico. This analysis applies to Mexican federal tax law — ISR (income tax), IVA (VAT) and SAT rules — and cites Mexican statutes. Amounts are in Mexican pesos (MXN).
Sales agents, board members, independent professionals and service providers of every kind get paid twice a month under a regime most of them never consciously chose: asimilados a salarios — salary-assimilated income (art. 94 of the LISR, the income tax law). The payer withholds "as if you were an employee," you receive a net amount, and that is where the explanation you were given ends. Everything else is missing: exactly what you are, which rights you do not have, when the arrangement works in your favor and when it is quietly costing you a fortune.
What an asimilado is (and is not)
Art. 94 allows certain income that is not wages to be taxed with the mechanics of wages: the payer withholds ISR from you using the rate table of art. 96 and issues you a payroll CFDI (the digital tax receipt). The relevant scenarios in practice: preponderant professional fees (fraction IV — more than 50% of your income from a single client, subject to prior written communication), optional professional fees (fraction V), optional business activity (fraction VI), commercial sales agents (the CFDI carries SAT code 08) and assimilated fees (code 09), plus board members and administrators — the latter with a special rule: their withholding cannot be lower than the top rate. What you are not: an employee. No IMSS (social security), no INFONAVIT (housing fund), no Afore (retirement fund), no aguinaldo (the mandatory Christmas bonus), no vacation, no PTU (mandatory profit sharing), no seniority. The word "salarios" in the name is pure withholding mechanics — it does not transfer a single labor right to you.
What the regime gives you
Genuine simplicity: you do not invoice, you keep no accounting, you file no provisional payments, and your services do not trigger IVA (VAT) — the payer absorbs the entire administrative burden. For someone starting out, billing moderate amounts, or providing services to a single client with no significant expenses, it is a comfortable and perfectly legal regime when the scenario is genuine.
The three traps
1. The consent they must ask you for — and almost no one does. The optional fractions of art. 94 require your written communication or consent: being assimilated is a choice of yours, not a unilateral decision by the payer. In practice, entire companies pay through asimilados without the recipient having signed anything — and the first warning is an unexpected payroll CFDI, with a withholding that doesn't match anything. If this is happening to you: demand the breakdown, the legal basis for the regime applied and the stamped CFDI; without that receipt you cannot credit the withholding they have already deducted from you.
2. The single-payer myth — and the real trap that replaces it. "You can't have two asimilados payers" is false as a general rule: the preponderance restriction applies only to fraction IV, and the different codes (08 sales agent, 09 fees) coexist with no technical conflict. The real trap is arithmetic: each payer withholds from you using the progressive rate table as if it were the only one, starting from the lowest brackets. Two or three payers = two or three fresh starts on the rate table = systematic under-withholding that turns into a surprise "balance due" on your annual return — which, by the way, becomes mandatory once you have multiple payers. Anyone paid as an asimilado from several sources must project their annual return during the year, not discover it in April.
3. The point where the regime becomes expensive. The convenience has a price: zero deductions and zero creditable IVA. You are taxed on gross income at progressive rates — which at high levels means the 35% marginal rate on every peso, with no way to deduct rent, equipment, travel or staff, and no way to recover the IVA on your expenses. A professional with high income and a real cost structure systematically pays more as an asimilado than under professional fees (deductions + creditable IVA) or through an appropriate vehicle. The regime that "simplified your life" at the start becomes the most expensive one in the catalog just as your income grows — and because the withholding is automatic, the excess cost is invisible: you never see the bill for the deductions you gave up.
How much is your payment arrangement costing you?
The diagnostic compares your real numbers across the three scenarios — asimilados, professional fees with deductions, corporate vehicle — with withholding, IVA, lost deductions and administrative burden all on the table. Above a certain income level, the annual difference runs into six figures; knowing it costs one session.
Frequently asked questions
Can they pay me as an asimilado without asking me?
The optional fractions require your written communication — the choice belongs to the taxpayer who receives the income, not to the one who pays. If the regime was applied to you unilaterally, you have the right to demand clarification of the legal basis, the corresponding payroll CFDI, and, going forward, to renegotiate the arrangement (professional fees under your own invoice, for example).
As an asimilado, do I have a right to IMSS or can I sue for seniority?
Not because of the tax regime itself — you are not an employee. But look at the substance: if in fact there is subordination (a set schedule, orders, the employer's tools, exclusivity), the relationship may be an employment one regardless of the paperwork, and then labor rights do exist and can be claimed. The name on the CFDI does not decide the nature of the relationship; the facts do.
I have two asimilados payers — how do I avoid the hit on the annual return?
Project it: add up your annual income from every source, run the annual rate table of art. 152, and compare it against the sum of the withholdings. The difference is your expected 'balance due' — set it aside monthly. With high income from a single payer the withholding almost works out on its own (you are already in the top bracket); the problem lives in mid-range income split across several payers.
When does it make sense to leave the asimilados regime?
When you have real deductible expenses, when your income consistently puts you in the top brackets of the rate table, or when you want to build structure (hire, invest, grow). The comparison of professional fees vs. asimilados vs. a company is run with your own numbers — and it is worth running every time your income changes scale.
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