Of all the documents in a customs clearance, the customs value declaration (manifestación de valor) is the one most importers underestimate — and the one that costs the most when something goes wrong. It isn’t a routine form: it’s the formal declaration, under the importer’s responsibility, of how much your goods are worth for customs purposes and how you arrived at that figure. Electronic transmission through VUCEM becomes mandatory on October 1, 2026. Here’s everything an importer should understand — and do now — before their next shipment.
Update, August 4, 2026. The MVE has been postponed again: the Third Advance Version of the Second Amendment to the 2026 General Foreign Trade Rules, published on July 31, moves it from August 1 to October 1, 2026. Through September 30 transmission remains voluntary and the previous scheme is still accepted. This is the fourth extension. What has not changed is the substance: customs value obligations already exist today, and the MVE only changes how they are presented.
What the customs value declaration is
It’s the document in which the importer declares the customs value of the goods and provides the elements used to determine it. In other words: you tell customs how much your cargo is worth, under what method you calculated it, and with what documents you back it up.
The Customs Law sets this out as an importer obligation (Article 59, section III). It isn’t optional, it isn’t discretionary, and — crucially — it isn’t the customs broker’s responsibility. The broker transmits the entry; the declared value and its backing are yours.
The big change: the Electronic Customs Value Declaration (MVE)
For years, the customs value declaration was a document the importer kept on file and handed to the broker, available in case the authority requested it. The reform to the Customs Law (Article 59-A) and rule 1.5.1 of the General Foreign Trade Rules changed that: the customs value declaration must now be transmitted electronically through VUCEM (Mexico’s Single Window for Foreign Trade), together with the worksheet for determining the value, before or at the time of clearance. That digital version is called the Electronic Customs Value Declaration (MVE).
The date that matters: October 1, 2026
The MVE’s mandatory date has been pushed back four times. The timeline, so you know where we stand:
| Date | What happened |
|---|---|
| Dec 9, 2025 | First effective date (Informative Note No. 8, VUCEM) |
| Apr 1, 2026 | First extension |
| Jun 1, 2026 | Second extension |
| Aug 1, 2026 | Third extension |
| Oct 1, 2026 | Current date (Third Advance Version of the Second Amendment to the 2026 General Foreign Trade Rules, published Jul 31, 2026) |
Through September 30, 2026 transmitting the MVE is voluntary: you can comply under the previous scheme without penalty for taking that route. From October 1, 2026 on, transmission through VUCEM is mandatory. The authorities have stated the extension is intended to give foreign trade users time to make operational adjustments and get familiar with the digital scheme.
How to read this run of extensions. Four postponements in under a year say something about the rollout, not about the obligation. Planning on the assumption that “they’ll surely move it again” is a bet — and the date is the only thing that has moved. The value file the MVE will ask for is the same one the authority can already require from you today in a review, MVE or no MVE. So the useful posture isn’t waiting for the next date; it’s having the file assembled, which pays off either way.
What to do with the extra time
If the extension caught you halfway, eight weeks is enough for what matters:
- Run a test transmission during the voluntary period, using a real, simple operation. It’s the only way to find out what you’re missing without a container riding on it.
- Check the importer’s e.firma: that it’s valid and not about to expire in October.
- Assemble the value file for your last three imports and confirm you can reconstruct the declared figure from documents. If you can’t do it for past shipments, you won’t manage it for new ones either.
- Decide who transmits: your company or the customs agency, and under what authorization. Put it in writing.
- Review your EXW and FOB purchases, where dutiable additions are most often forgotten.
What you need to transmit the MVE
- A valid e.firma (FIEL) for the importer.
- An active RFC with no restrictions.
- The supporting information and documentation for each operation (invoice, transport, insurance, royalty contracts, etc.).
- The customs value worksheet.
Who’s responsible (still the importer)
The MVE is transmitted by the importer — or a third party they expressly authorize. If you don’t give your customs broker explicit authorization to consult or transmit it, the obligation falls directly on you. The broker clears the entry; the MVE and its backing are the importer’s responsibility, just as before — only now it’s recorded electronically and the authority cross-checks it instantly.
That means it’s no longer a paper in a filing cabinet just in case: it’s data the SAT receives and compares. A declared value that doesn’t match the invoice, price databases or comparable transactions raises flags far more directly than before.
There are narrow exceptions (certain temporary imports under international conventions, cultural/sports events, filming equipment, test vehicles, research; operations under complementary global entries). But for a typical commercial import operation, the MVE applies.
How customs value is determined
Mexico follows the WTO Valuation Agreement. The primary method — and the one that applies to the vast majority of imports — is the transaction value: the price actually paid or payable for the goods, adjusted by the dutiable additions.
The price is not the customs value
This is the most common conceptual error. The customs value is not just what you paid for the product. To the invoice price you have to add certain items that don’t always appear on it:
| Dutiable addition | Example |
|---|---|
| Freight to the point of introduction into Mexico | Ocean freight to the Mexican port |
| Cargo insurance | The transport insurance premium |
| Loading, unloading and handling costs | Up to the place of introduction |
| Commissions (except buying commissions) | Sales agent commission |
| Packing and container costs | Forming a whole with the goods |
| Royalties and license fees | A condition of the sale of the goods |
| Materials or services supplied by the buyer | ”Assists” — molds, designs, tools |
If you buy on EXW or FOB terms, much of this cost isn’t on the supplier’s invoice but must still be added to the customs value. Forgetting it is undervaluation — even in good faith.
When transaction value doesn’t apply
If there’s a relationship between buyer and seller that affects the price, if there’s no real sale, or if the price isn’t reliable, you fall back, in order, to the secondary methods: value of identical goods, of similar goods, deductive value, computed value, and finally the “fall-back” method. Most importers never leave transaction value — but you should know the hierarchy exists.
The worksheet
It accompanies the customs value declaration and is where you show the arithmetic: invoiced price, additions added, deductions subtracted, exchange rate, and the final customs value. It’s your calculation record. If the authority questions the value, this worksheet is your first line of defense — provided it’s well built and backed by real documents (invoice, insurance policy, freight contract, license agreement, etc.).
What happens if you get it wrong — or skip it
| Situation | Consequence |
|---|---|
| Not transmitting the MVE (from Oct 1, 2026) | Violation; clearance may not proceed |
| Undervaluing (declaring less than the real value) | Omitted contributions, fines, surcharges; presumption of undervaluation |
| Omitting dutiable additions | Tax differences when detected; tax assessment |
| Insufficient documentary support | Authority query, possible rejection of the declared value |
| Undervaluation with signs of intent | PAMA, precautionary seizure, severe sanctions |
Undervaluation is one of the SAT’s priority enforcement targets. Declaring an artificially low value to pay less duty and VAT is not only detectable — with estimated-price databases and electronic transmission — but it drags the importer into tax assessments that are usually far larger than the initial “saving.”
The most common SME mistake
Declaring as customs value only the commercial invoice amount, without adding international freight or insurance, because “those are on another quote.” On an FOB Shanghai purchase, the ocean freight and insurance to the Mexican port are mandatory dutiable additions. Omitting them artificially lowers the taxable base and constitutes undervaluation, even if the intent was just to “declare what’s on the invoice.” Customs doesn’t distinguish between carelessness and intent when collecting differences — it distinguishes afterward, to aggravate the penalty.
How it fits with the rest of the clearance
The customs value declaration doesn’t live alone. It cross-references:
- The tariff classification, because the customs value is the base on which that code’s duty is applied.
- The customs clearance, because without a transmitted value declaration the entry doesn’t move.
- The logistics costs, because the freight and insurance you pay are precisely the dutiable additions you must declare.
Having the customs value solid before arrival prevents queries that stop the container and trigger demurrage and storage.
At TradeWay
The extension to October 1, 2026 bought eight more weeks, and most importers still don’t have their MVE process ready. The customs value declaration is the importer’s responsibility, but it’s rarely something the importer should assemble alone — and now, with mandatory electronic transmission, mistakes are recorded instantly.
Because we handle the full operation — forwarding, clearance and valuation under a single point of contact — we know exactly how much you paid in freight and insurance, which dutiable additions apply to your purchase, and how to build the worksheet that backs the declared value. We help you:
- Get your MVE ready to transmit through VUCEM before October 1, with your e.firma and supporting documentation in order — and test it during the voluntary period, not on the first mandatory day.
- Validate your customs value including every dutiable addition, so it withstands a review rather than inviting one.
- Define the authorization scheme between your company and the customs broker, so responsibility is clear.
If you’re not sure you’ll be ready by October 1 — especially if you buy EXW or FOB — get in touch today and we’ll review your last operation before the SAT does.
