Tax Materiality in Mexico.
Tax Materiality in Mexico: How Business Groups Should Support Their Transactions Before an SAT Review In a group with several
Most foreign groups decide how to fund a new Mexican subsidiary at the last minute, often when the first payroll or equipment invoice is due. The quickest option is usually an intercompany wire booked as a loan. That choice has Mexican tax consequences that are hard to undo: whether interest is deductible, how much tax must be withheld when it is paid, what the subsidiary must report, and how cash can later come back to the parent.
This guide is for CFOs, corporate counsel and investors outside Mexico. It covers the decisions to make before funding a Mexican subsidiary, from the business model and the entity to the choice between equity and debt and the reporting that follows. It addresses Mexican rules only; the treatment in the parent’s country should be reviewed with an adviser qualified there.
Executive summary
Funding should follow the business plan, not the other way around. Before choosing equity or debt, define what the subsidiary will do (manufacture, distribute, provide services), who will sign with Mexican customers, what assets and people it will have, and when it expects to be profitable. Those facts determine the subsidiary’s taxable profile, its transfer pricing position and how much leverage it can support.
Mexico’s Foreign Investment Law allows foreign investment in any proportion in Mexican companies [1], with exceptions. Certain activities are reserved to Mexicans, some have percentage caps, and others require prior approval from the National Foreign Investment Commission to exceed 49%. Check the activity before structuring. Once a foreign investor holds shares, the subsidiary must register in the National Foreign Investment Registry (RNIE) within 40 business days and renew its registration annually through an economic and financial questionnaire [1].
The two most common entity types, the sociedad anónima de capital variable (S.A. de C.V.) and the sociedad de responsabilidad limitada de capital variable (S. de R.L. de C.V.), are taxed in the same way in Mexico. The difference often matters at home: for U.S. federal tax purposes, a Mexican sociedad anónima is on the list of entities always treated as corporations, while the S. de R.L. de C.V. is generally an entity that may elect its classification [11]. That decision belongs to the parent’s U.S. adviser and should be made before incorporation. For a broader view of entity and setup mistakes, see Common Mistakes Foreigners Make When Starting a Business in Mexico.
| Question | Equity (capital contribution) | Intercompany loan |
|---|---|---|
| Is it taxable when received? | No. Capital increases are not income for the subsidiary [2] | No; it is a liability |
| Deduction in Mexico | None | Interest, if at arm’s length and within the thin capitalization and net interest limits [3][4] |
| Withholding when paid | Dividends follow separate rules | Interest paid to a foreign related party that is not a bank: up to 35% under domestic law, reducible by treaty [5][6] |
| Returning cash to the parent | Capital reductions are tested against the contributed capital account (CUCA); amounts above it, and in some cases retained earnings, are treated as distributed profits [8] | Principal repayment, with interest taxed as above |
| Main risk | Cash trapped if the subsidiary has no profits or capital to return | Disallowed interest or interest recharacterized as a dividend [3][9] |
Neither option is better in every case. A start-up subsidiary with years of expected losses gets little benefit from interest deductions and may simply accumulate withholding costs. A profitable subsidiary with stable cash flow may justify a measured amount of debt.
Interest on the portion of debt that exceeds three times the subsidiary’s equity is not deductible when that debt is owed to related parties resident abroad [3]. The excess is calculated using the average annual balance of all interest-bearing debt minus three times average equity (the average of opening and closing capital contable, the accounting equity). If debt with foreign related parties exceeds that excess, only a proportional part of its interest is disallowed. Early-year losses reduce equity, so a structure that passes the test on day one can fail by year end. The law allows a higher ratio if the taxpayer shows its activity requires more leverage and obtains a ruling from the SAT, and it lets companies measure equity using certain tax accounts instead of accounting equity, within limits [3].
Separately, net interest that exceeds 30% of “adjusted taxable profit” (a tax measure similar to EBITDA) is not deductible. This limit applies only when interest accrued in the year exceeds MXN 20 million, a threshold shared among related Mexican entities [3].
Interest is deductible only if it matches what unrelated parties would agree; any excess over market value is not deductible [4]. Mexican law also treats interest as a dividend in specific cases, including loans the creditor can call at any time, loans where the creditor can step into management on default, interest tied to profits, and “back-to-back” loans, a category that includes financing without a business purpose [9]. For the business purpose standard, see Business Purpose in Mexico.
Interest paid to a foreign parent that is not a financial institution falls under the residual rule of Mexico’s withholding article, at the top rate of the individual tariff, currently 35% [5]. A tax treaty with the lender’s country can reduce that rate, but Mexico grants treaty benefits only to a lender that proves residence in the treaty country and meets the treaty’s terms and the procedural rules of Mexican law; for related-party payments, the SAT may also ask for a statement that the income is taxed in the lender’s country [6]. Payments abroad are deductible only if the withholding is made and paid [10].
Illustrative example; it does not describe a client or a real case.
A U.S. company is setting up a distributor in Guadalajara that needs MXN 50 million in its first year. It compares two options: all equity, or MXN 10 million of equity plus a MXN 40 million loan from the parent at 10% annual interest.
Under the loan option, and assuming balances stay constant through the year:
| Item | Amount (MXN) |
|---|---|
| Average equity | 10,000,000 |
| Debt allowed before the thin cap limit applies (3 × 10,000,000) | 30,000,000 |
| Average loan from the parent | 40,000,000 |
| Excess debt | 10,000,000 |
| Annual interest (10% × 40,000,000) | 4,000,000 |
| Non-deductible interest (4,000,000 × 10,000,000 ÷ 40,000,000) | 1,000,000 |
| Interest potentially deductible, if at arm’s length and withholding is paid | 3,000,000 |
| Domestic withholding on interest paid (35%), before any treaty reduction | 1,400,000 |
The 30% net interest limit would not apply because interest is below MXN 20 million, assuming no other related Mexican entity carries debt. If the distributor posts a first-year loss, its average equity falls and more interest becomes non-deductible, while withholding is still due when interest is paid. In that scenario, the group should compare the withholding cost and the parent’s ability to credit it at home with the value of a deduction the subsidiary may not use for several years.
Whatever the mix, the documentation should exist before the money moves:
The 2027 income tax reform was approved by Mexico’s Chamber of Deputies on October 14, 2026, and by Senate committees on October 21; at the time of writing (October 26, 2026), it is scheduled for a Senate floor vote and still requires publication in the DOF, Mexico’s Official Gazette [12]. As approved by the Chamber of Deputies, it would lower the net interest limit from 30% to 20% of adjusted taxable profit, allow payments abroad to be deducted only in the year they are actually paid, and cap total deductions for companies with income above MXN 50 million [12]. These are proposals until published; funding plans for 2027 should be reviewed against the final text.
Does Mexico tax a capital contribution to a subsidiary?
No. A capital increase is not income for the receiving company [2]. Notarial, registry and RNIE formalities still apply.
Can a U.S. parent claim a reduced withholding rate on interest?
Possibly, under the U.S.–Mexico tax treaty, if the parent proves its U.S. residence and meets the treaty’s conditions and Mexico’s procedural rules [6]. Without that support, the Mexican subsidiary must withhold at the domestic rate [5].
Can we start with a loan and convert it to equity later?
Capitalizing a loan is common, but its tax effects, including on the contributed capital account, depend on how it is documented and on rules that the 2027 reform proposes to change. Review the conversion before it happens.
Before funds move, Tax Art can review your business plan, proposed entity and funding mix and deliver, within the agreed scope, a comparison of equity and debt scenarios under Mexican rules, a thin capitalization and withholding analysis, and a calendar of registration and reporting obligations for your Mexican subsidiary.
Request a pre-investment tax assessment for your Mexican subsidiary
Learn more about our Tax Counseling team.
This article is for information only and reflects the rules reviewed as of October 26, 2026. It does not replace an analysis of each investor’s facts or advice on the tax rules of the parent’s country.
Tax Materiality in Mexico: How Business Groups Should Support Their Transactions Before an SAT Review In a group with several
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