Paying Mexican Contractors as a U.S. C-Corp: The 1099 Trap

Your first engineer in Guadalajara starts Monday. Your ops person sends them a W-9, adds them to Gusto as a 1099 contractor, and in January you mail them a 1099-NEC.

Every step of that is wrong, and none of it is the part that will cost you money.

The W-9 is for U.S. persons. A Mexican national living in Mexico isn't one, and they can't legally complete it. The right form is a W-8BEN. And the 1099-NEC you mailed? You didn't owe one. Compensation for personal services is sourced to where the services are physically performed — IRC §861(a)(3) and §862(a)(3) — not where the payer sits, not where the contract was signed, not where the money left from. Your engineer worked in Jalisco. That's foreign-source income. No 1099-NEC, no U.S. withholding, no Form 1042-S, nothing filed.

So the paperwork you were anxious about was never the exposure. Collect a W-8BEN, keep it in your files, move on.

The exposure is on the Mexican side, and almost nobody looks there until something forces them to.

This is the third post in the cross-border cluster. Delaware C-Corp vs Mexican S.A. de C.V. covered picking the structure. SAT Compliance for a U.S.-Funded Mexican Subsidiary covered operating one. This one covers the stage before either: you have no Mexican entity, you're paying people in Mexico anyway, and you need to know whether that's fine.

The question isn't "1099 or not." It's "contractor or employee, under Mexican law."

Mexico doesn't care what your agreement is titled. It doesn't care that the person signed something labeled "Independent Contractor Agreement," and it doesn't care that you've never set foot in the country.

Mexican labor law applies a subordination test — subordinación. If a relationship has it, the person is an employee, full stop, regardless of paperwork. Three tests determine where you actually stand. Run all three. Most founders run none.

Test 1 — Where are the services performed?

This is the one that governs your U.S. obligations, and it's the easy one.

Services performed entirely in Mexico: foreign-source income. Collect a W-8BEN (individual) or W-8BEN-E (entity), file nothing with the IRS, withhold nothing.

Services performed in the United States — your contractor flies to Austin for a two-week onsite, attends your offsite in Miami, works from a co-working space in San Diego for a month — that portion becomes U.S.-source. Now you're in 30% withholding and Form 1042-S territory unless a treaty position applies.

Founders get this wrong in one specific way: they bring the Mexican team to the U.S. for an annual offsite, pay them their normal monthly invoice for that month, and never allocate the days. It's a small number and rarely audited. It's also the kind of thing that turns up in diligence as evidence you weren't tracking, which is worse than the tax itself.

Track the days. A column in a spreadsheet is enough.

Test 2 — Is the relationship subordinate?

Here's where the money is.

Mexican courts look past the contract title at how the relationship actually runs. The markers that point to employment:

• Fixed hours. You expect them online 9–6 Mexico City time.
• Direction and control. You tell them how to do the work, not just what outcome you need.
• Your tools, your systems. You issued the laptop, the email address, the Slack seat.
• Exclusivity. They work only for you and can't take other clients.
• Integration. They're on the org chart, in standups, doing the same work as your U.S. employees.

Read that list honestly. If you hired a full-time senior engineer in Monterrey who works your hours, uses your laptop, sits in your standup, reports to your VP Eng, and has no other clients — that's an employee under Mexican law. The invoice they send you every month doesn't change it.

What it costs when a court agrees. The person files a demanda laboral, usually after you end the relationship. If they win, you owe the employment package retroactively:

• Severance: three months' salary, plus 20 days' salary per year of service, plus the seniority premium
• Aguinaldo: minimum 15 days of wages per year, mandatory under Article 87 of the Federal Labor Law, payable by December 20 — not waivable, not replaceable
• Vacation: 12 days in the first year since the 2023 Vacaciones Dignas reform, rising two days a year to 20, plus the 25% vacation premium
• IMSS: social security contributions you never made, with a five-year lookback and fines running 40–100% of the omitted amount

Statutory employer burden in Mexico runs roughly 25–35% on top of base salary. If you've been paying a "contractor" $6,000/month for three years and it gets reclassified, you're looking at well into six figures between back contributions, fines, and the severance award.

That's the trap. Not the 1099.

Test 3 — Does this person bind your company in Mexico?

The third test is the one almost no founder has heard of, and it's the one that can create a Mexican corporate tax filing obligation out of nothing.

Under Article 5 of the U.S.–Mexico tax treaty, a dependent agent who has and habitually exercises authority to conclude contracts in your company's name creates a permanent establishment — establecimiento permanente — for your U.S. company in Mexico. A PE means Mexico can tax the profits attributable to it, and you now have a Mexican corporate filing obligation for a company you thought had no Mexican presence at all.

An agent of genuinely independent status, acting in the ordinary course of their own business, doesn't create one. That's the distinction.

In practice this almost never bites engineering hires. It bites the first sales hire. You bring on a "contractor" in Mexico City to sell into the LATAM market, they negotiate and close deals in your name, and you've potentially established a taxable presence — before you ever considered incorporating.

If your first Mexican hire is customer-facing with signing authority, get an opinion before they close anything. This is the single most expensive thing on this page to unwind after the fact.

What your contractor owes on their side

Even when all three tests come back clean, your contractor has obligations you should verify they're meeting — because if they're not, they're the one exposed, and an exposed contractor becomes your problem eventually.

A Mexican persona física providing professional services has to issue a CFDI — the SAT electronic invoice — for income, including income from foreign clients. Invoicing a U.S. company, they use the generic foreign RFC XEXX010101000 with tax regime 616, "Sin obligaciones fiscales." No special registration required; it's built into CFDI 4.0.

Ask for the CFDI. Two reasons: it confirms they're actually registered with SAT rather than operating informally, and it gives you a clean documentation trail if anyone ever asks what these payments were.

If your "contractor" can't produce a CFDI, you don't have a contractor relationship. You have an undocumented employment relationship with a five-year lookback attached.

When you actually need an entity — and the number is smaller than you think

Conventional wisdom says stay on contractors until you have "real scale" in Mexico, then incorporate. That's wrong, and the math isn't close.

Your two compliant options for genuine employees:

Employer of Record. A local entity employs the person on your behalf. Management fees run $300–$700 per employee per month, commonly $499–699. Fast, no entity to maintain.

Your own Mexican entity. Setup runs about $3,500–$4,500 one-time — notary, capital, legal, RFC, IMSS and INFONAVIT registration. Ongoing accounting, payroll, CFDI issuance and IMSS filings run roughly $1,000–$1,500/month, flat, regardless of headcount.

That last phrase is the whole decision. EOR scales linearly with people. An entity is a fixed cost.

At $1,250/month of entity overhead against $550/month per head of EOR fees, the crossover is between two and three people. Not twenty. One published three-year comparison for five employees puts it at roughly $81,000 in EOR fees versus $40,000–$62,000 all-in for incorporation plus 36 months of compliance.

One nuance that trips up the comparison: the 25–35% statutory employer burden applies either way. It's not an EOR fee and it's not an entity cost — it's the cost of employing someone in Mexico. Strip it out of both sides before you compare, or you'll conclude the EOR is cheaper when it isn't.

Where EOR still wins: one or two hires, a market test you might reverse, or no appetite to oversee a foreign entity. Where the entity wins: three or more people, anything long-term, IP-sensitive work, or local invoicing. Note the asymmetry — EOR is the reversible choice, which is worth something real when you're not sure the market works.

You probably don't need any of this

If you have one person in Mexico doing project work on their own schedule, with their own equipment, for you and two other clients, who sends you a CFDI every month and has never attended a standup — you have a genuine contractor. Collect the W-8BEN, keep the CFDIs, and stop reading. There's nothing here for you.

The same goes if you're paying a Mexican agency or dev shop that invoices as a company and staffs the work itself. That's a vendor relationship, not an employment question.

I'd rather tell you that than sell you a structure you don't need. Most U.S. startups with one or two Mexican contractors are fine. The ones that aren't fine usually know it already — they just haven't priced it.

The cleanup checklist

If you're already paying people in Mexico and reading this with a sinking feeling, here's the sequence:

1. Swap the W-9s for W-8BENs. Retroactively. Takes an afternoon.
2. Stop issuing 1099-NECs for services performed in Mexico. If you've filed them, talk to your CPA about whether to correct — usually harmless, occasionally not.
3. Run Test 2 honestly on every person. Hours, control, tools, exclusivity, integration. Write down the answer for each.
4. Collect CFDIs going back as far as you can. Anyone who can't produce them is your highest-risk relationship.
5. Flag anyone customer-facing with signing authority for a PE opinion.
6. Count your genuine employees. Three or more, price the entity against the EOR. Under three, the EOR is probably right.
7. Do this before you open a round, not during. Every item above is cheap to fix on a quiet Tuesday and expensive to fix with a term sheet outstanding.

I'm a CFO, not your attorney or your contador. Everything above is how I've seen this structured and where I've seen it break. Before you act on any of it, get a Mexican contador and a U.S. CPA who have each done this specific thing before — and if the same firm claims both, ask which one of them has actually filed a CFDI.

If you're paying people in Mexico

Three ways to take this further, depending on where you are:

• Not sure whether your finance operations can survive diligence? The Raise-Ready Scorecard takes four minutes and scores you across six dimensions, including the operational infrastructure investors probe first.
• Want to model what an entity actually costs you? The CFO Toolkit has burn and runway calculators — run the entity overhead as a new fixed cost and see what it does to your runway before you commit.
• Already have people in Mexico and want this cleaned up? Our Lean Finance Stack Setup is the operational fix: contractor documentation, CFDI collection, the classification review, and the entity-versus-EOR decision, done once and done right. If you need someone who stays — through the entity setup, the first Mexican payroll, and the diligence conversation on the other side — that's the Fractional CFO engagement.

Or just book 30 minutes and tell me who you're paying and how. I can usually tell you in that call whether you have a problem or not.