Contemporaneous transfer pricing documentation and evidence retention

Executive answer #

Contemporaneous documentation is evidence created, approved and retained while a related-party transaction is designed and performed. It includes agreements, requests, deliverables, decisions, source data, calculations, invoices, payments, reconciliations and exceptions. The annual transfer pricing report uses that evidence to explain functions, method and result; it cannot replace evidence that never existed.

Article 76, section IX, of the Mexican Income Tax Law requires corporate taxpayers within its scope to obtain and retain supporting documentation for related-party transactions. Articles 179 and 180 establish the substantive standard and methods. The Federal Tax Code governs accounting records and general retention periods, with circumstances that may extend availability. The practical response is not a universal “five-year” label on every file. Each record should be classified by the act it supports and its applicable retention rule.

A strong file is produced in stages. Before signature, it records the decision. During performance, it proves the asset, service, financing or right. At invoicing and settlement, it connects the consideration. At year-end, it reconciles and tests the price. At filing, it preserves the exact version supporting each reported answer. Rebuilding those layers years later is more expensive and less reliable.

The report and the evidence serve different purposes #

A transfer pricing report usually describes the group, transaction, functional analysis, method selection, comparable set and conclusion. It is a technical narrative based on information. Contemporaneous evidence answers where that information came from and what actually happened.

A report may state that Mexico received technology support. The evidence should show requests, access, tickets, meetings, configurations, owners and acceptance. It may state that a foreign entity controlled credit risk. The file should identify who approved limits, monitored customers and decided exceptions. It may conclude that a loan had a three-year term. The agreement, drawdown, schedule, covenants and conduct should agree.

This distinction becomes decisive in an audit. An adviser-prepared report may be technically sound, but the tax authority can compare it with messages, systems, electronic invoices, ledgers, payments and returns. If the facts conflict, adding pages to the report does not cure missing conduct or evidence.

Principles of a defensible file #

Temporal proximity #

Capture evidence near the time it arises. An approval dated before a transaction is performed explains the decision better than minutes created years later. This does not mean retaining every email. It means designing meaningful milestones that produce reliable records.

Traceability #

Give every dealing an identifier linking the agreement, cost center, ledger account, Mexican electronic invoice or foreign document, settlement, pricing method and return. Traceability allows the company to reproduce a number and prove that the transaction population is complete.

Authenticity and version control #

Retain author, date, approval and version. An undated policy or amended agreement without history creates uncertainty. Final files should be protected from silent changes, with authorized access and reliable backups.

Proportionality #

Depth depends on amount, complexity and risk. A small pass-through expense does not require the same analysis as an intangible transfer. Proportionality does not mean making transactions disappear: inventory and classify them first, then assign an evidence tier.

Cross-document consistency #

Agreement, conduct, accounting, price and disclosure should describe the same transaction. Legitimate differences—accrual versus payment, functional currency versus invoice, or forecast versus closing result—need a documented bridge.

Evidence calendar by stage #

The calendar should state frequency, owner, location and format. It should also define the response to missing evidence: who receives escalation, whether performance or payment pauses, what substitute may be accepted and how the exception is approved.

If the annual report is the first time the team searches for agreements and deliverables, implement an evidence calendar before the next cycle.

Evidence by transaction type #

Intragroup services #

Retain the service catalog, request, scope, providers, recipients, time or activities, deliverables, benefit, costs, allocation key, markup and acceptance. Separate shareholder activity, duplication and incidental benefit. An agreement and invoice alone do not prove performance.

Purchases and sales of goods #

Integrate specifications, orders, volume, quality, delivery terms, warranties, discounts, inventory, logistics and internal comparables where available. Link imports to customs entries and declared value. Document returns, obsolescence and price adjustments.

Financing #

Retain funding need, alternatives, repayment capacity, approval, agreement, drawdown, currency, term, security, rating, benchmark, schedule, interest and conduct. Monitor balances and covenants. A long-standing current account may need to be reassessed as debt.

Intangibles and royalties #

Identify rights, territory, exclusivity, useful life, legal ownership and the functions that develop, enhance, maintain, protect and exploit the intangible. Document actual use, royalty base, sales, campaigns, approvals and value. Legal title alone does not explain the return.

Adjustments and extraordinary transactions #

For true-ups, preserve the calculation, cause, approval, invoice or other document, entry, settlement and effects on other taxes. For restructurings, asset or share transfers, include the before-and-after model, realistically available alternatives, valuation, negotiations and approvals. These files may require enhanced retention because their effects continue over future years.

Build a retention policy, not a deletion shortcut #

Article 30 of the Federal Tax Code establishes general rules for retaining accounting and tax-supporting documentation and includes special situations. Corporate records, acts with continuing tax effects, tax losses, loans and transactions affecting later years may need to remain available beyond a simplified reading of the general period. An audit, appeal, mutual agreement procedure or litigation may also justify a legal hold.

The policy should therefore classify documents instead of applying one automatic deletion date. For every category, record legal basis, start date, ordinary period, extension, owner and hold event. Tax and legal should approve the schedule; IT should implement it in applications and backups.

Retention does not mean collecting without order. A repository full of duplicates, drafts and ownerless records makes it difficult to identify the version actually used. The master index should distinguish final documents, supporting evidence, calculations, external sources and relevant correspondence. Personal and confidential data require access controls and security.

A reproducible file architecture #

An intercompany file can use eight layers:

1. Governance: perimeter, policy, owners, calendar and approvals.
2. Counterparty: identity, residence, relationship and organization chart.
3. Transaction: agreement, appendices, amendments and characterization.
4. Performance: deliverables, decisions, use records and acceptance.
5. Finance: subledgers, invoices, payments, withholding and reconciliation.
6. Economics: functional analysis, method, comparables, calculations and true-ups.
7. Compliance: returns, workpapers, filing receipts and cross-checks.
8. Exceptions: deviations, cause, approval and remediation.

Use stable names, metadata and an index that does not depend on one employee’s memory. The repository should retrieve files by entity, counterparty, dealing, period and return. Avoid links to personal folders or vendor systems without an export and handover protocol.

Test auditability #

Before closing the file, select a sample in both directions. First, take a reported number and trace it to the trial balance, invoice, agreement, delivery and method. Second, take a dealing from the subledger and trace it forward to the report and returns. The first test verifies support; the second verifies completeness.

Ask someone who did not prepare the file to reproduce the calculation using the index. Record missing data, manual dependencies and contradictions. Response time is itself a useful indicator. If reconstructing one transaction takes days, the model is not ready for a high-volume information request.

Common errors #

1. Signing backdated agreements without explaining when conduct began.
2. Retaining final outputs without source data or approvals.
3. Saving large email sets without identifying which message proves the fact.
4. Using screenshots without date, system or owner.
5. Documenting price while omitting service existence or benefit.
6. Separating report, invoices, ledger and return without reconciliation.
7. Applying one deletion period to records with future-year effects.
8. Depending on personal folders or vendors without a handover protocol.
9. Failing to place a hold when an audit or dispute starts.
10. Overwriting the version that supported a filed return.

Governance and metrics #

Tax defines the requirements; each business function produces its evidence; legal controls agreements and retention; IT maintains access and backup; internal audit can test the process. A quarterly committee reviews missing agreements, overdue deliverables, open reconciliations, exceptions and records approaching deletion.

Useful metrics measure coverage, not document volume: percentage of dealings with an owner, current agreement, performance evidence, reproducible calculation, reconciliation and return link. Also monitor days to close a gap and the percentage of adjustments identified before year-end.

Related topics #

• PT-005: anatomy of the transfer pricing report.
• PT-016: transaction inventory from the trial balance.
• PT-031: intragroup services.
• PT-050: financial transaction defense file.
• PT-083 and PT-084: defense file and materiality.

Contemporary-evidence calendar #

Assign evidence to the moment it naturally arises. At contracting, retain need, approvals, agreement and initial analysis. Monthly, archive invoices, entries, deliverables, acceptance, indicators and reconciliations. Quarterly, review profitability, deviations and functional changes. At close, document adjustments, conclusions and consistency with returns. The study then summarizes controlled facts instead of recreating them.

Define an owner, repository, format, retention period and backup for every item. Links must survive staff and system changes. Preserve original versions, dates and metadata; a screenshot without provenance may lose value. Sensitive communications receive appropriate access without making the operating file invisible.

Test the calendar through samples and log missing items while prospective correction remains possible. Do not manufacture historical proof. Where support does not exist, document the limitation and decision. Contemporaneous documentation is an operating and governance practice, not a cover page dated at year-end.

Sources and verification date #

• Mexican Income Tax Law, current text, Articles 76, 76-A, 179 and 180.
• Mexican Federal Tax Code, current text, particularly Articles 28 and 30.
• 2026 Miscellaneous Tax Resolution, subject to subsequent amendments.
• OECD Mexico Transfer Pricing Country Profile, a technical reference that does not replace Mexican legislation.

Sources checked on August 2, 2026. Specific retention periods must be determined by document, facts, fiscal year and any open proceeding. This article does not replace advice for a particular case.

Request an Evidence Calendar to assign evidence, owners, frequency, repository and retention treatment to every material intercompany dealing.