MexCo, IrishCo, USCo: A Three-Country Transfer Pricing Squeeze
IrishCo, the principal of a $1.4 billion industrial group, buys finished assemblies from its Mexican subsidiary MexCo and resells them to the group's US sales company. MexCo's total costs are $64 million (materials $52 million; labour, overhead and depreciation $12 million) and it invoices IrishCo $69.1 million, an 8% markup on total cost. IrishCo resells to the US company at $96 million; the US company sells at $115 million with $9 million of operating costs. The group's effective tax rate is 11.8%, with Ireland at 12.5%, Mexico at 30% and the United States at 21%. The group's brand, design and process intangibles sit in Ireland, having been purchased from the US parent in 2016 for $40 million. Mexico's tax authority has audited MexCo, arguing that it carries genuine inventory and warranty risk and owns the moulds, and proposes a 12% markup on total cost. The IRS has separately proposed a $9 million increase in US taxable income, arguing the 2016 migration was priced incorrectly. Both cases are at the discussion stage.
1. Identify the tested party and profit level indicator you would defend, and assess whether the proposed Mexican adjustment is supportable.
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Function first, then the indicator. MexCo performs manufacturing, holds inventory, carries warranty obligations and owns the moulds. It owns no intangibles, has no customer relationships and does not set price. That makes it the least complex party and the natural tested party under a transactional net margin method, with operating margin on total cost as the indicator, because it controls the cost base.
Test the contract against conduct. The 8% markup is only defensible if MexCo genuinely bears inventory and warranty risk. If the manufacturing agreement contractually passes both back to IrishCo, then the conduct is limited-risk toll manufacturing, a 3–6% markup is the right range, and the Mexican authority is right that something is off - but wrong about the direction. If MexCo truly bears the risk, 8% sits at the low end of a defensible 7–10% band and a 12% claim is outside it and should be resisted with a benchmarking study.
The IRS argument is different in kind. A $9 million shift to the US is an attack on the DEMPE analysis and the 2016 buy-in price for intangibles, not on MexCo's markup. It cannot be answered by a Mexican benchmarking study. It requires a valuation defence of the 2016 transfer and evidence of where development, enhancement, maintenance, protection and exploitation actually occur.
Practical first step: reconcile the intercompany contracts with actual conduct before either authority gets a written submission that contradicts the facts.
2. Quantify the exposure and decide whether to pursue a bilateral advance pricing arrangement or litigate in each country.
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Quantify the two adjustments separately. The Mexican proposal adds 4% of $64 million, or $2.56 million, to Mexican profit: at 30%, roughly $0.77 million of extra tax. The US proposal adds $9 million at 21%, roughly $1.89 million. Naively these are not offsets - they hit different entities - so without relief the group could pay tax twice on the same profit.
What relief is available. The US–Mexico treaty provides mutual agreement procedures, but MAP is slow and outcomes are uncertain. A bilateral APA covering the MexCo–IrishCo and IrishCo–USCo transactions gives prospective certainty, typically takes 24–36 months and costs roughly $250,000–$400,000 in advisory and benchmarking work. Rollback to prior years is negotiable and is the main prize here, because the audit years are exactly where the double tax sits.
Decision logic. If the combined disputed profit is around $11.5 million and the credible double-taxed portion is several million dollars, the APA is clearly cheaper than litigation in two jurisdictions with no guarantee of symmetry. If the Mexican adjustment can be settled unilaterally inside the benchmark range, limit the APA to the US intangible issue.
Precondition: the contracts must match conduct before filing, or the APA will be built on a factual record that contradicts the group's own documents.
3. How does a 15% global minimum tax change the group's willingness to fight for Irish profit?
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Recalculate the value of the structure. IrishCo books roughly $26.9 million of profit at a 12.5% rate. Under a 15% minimum tax with jurisdiction-by-jurisdiction blending, that profit attracts a top-up of about 2.5 percentage points, roughly $0.67 million a year, unless Ireland's own qualifying regime captures it. The group's 11.8% effective rate is therefore no longer a 9-point advantage over the US rate; it is closer to a 6-point advantage over 21%, and in some configurations less.
This reframes the dispute. Profit conceded to the US at 21% carries no top-up tax, so the marginal cost of losing the IRS argument is lower than the headline 21% suggests - part of it was going to be paid anyway. Profit conceded to Mexico at 30% likewise attracts no top-up. Fighting to retain profit in Ireland preserves a shrinking benefit while generating two audits and an unquantified double-tax risk.
Recommended posture: concede a negotiated portion of the US adjustment, on the basis that the 2016 valuation was defensible but the group will accept a revised buy-in payment. In exchange, secure IRS support for the Mexican markup, or at least non-objection, which removes the double-tax exposure. That trades a low-value tax benefit for certainty and for protection of the manufacturing footprint.
Caveat: confirm the top-up mechanics and any qualified refundable tax credit treatment before conceding, because the interaction with credits is where this analysis can reverse.