MID Construction: How to Build a Manufacturer ID Code in ACE

Key Points

• MID construction is a mechanical rule in the CBP Form 7501 (02/26) instructions, so the code is derived from the manufacturer's name and address, never looked up in a registry.
• The rule combines the manufacturer's ISO country code, the first three characters of each of the first two name words, up to four numeric characters of the street address, and the first three characters of the city.
• The same factory must always yield the same MID and different factories must yield different MIDs, because CBP targeting, AD/CVD suffix checks and textile verification key on the code.
• The most common errors are counting articles or trade terms such as The, Company or Ltd as name words, using a post office box or suite number for the address digits, inconsistent city spellings, and building the code from the seller instead of the manufacturer.
• For textiles, 19 CFR 102.23 makes the identity of the origin-conferring manufacturer especially important, so the MID must reflect that party.

On this page

1. At a glance
2. Where does the MID construction rule come from?
3. How does MID construction work, element by element?
4. Who is responsible for MID construction and when does it happen?
5. Common MID construction errors
6. How MID construction interacts with other ACE and ABI terms
7. Frequently asked questions
8. What importers and brokers should do
9. Key references

MID construction is CBP's rule for building a Manufacturer Identification code from the manufacturer's ISO country code, the first three characters of the first two words of its name, up to four digits from its street address number, and the first three characters of its city. Customs brokers and importers apply MID construction when preparing entry lines, so the resulting code is a derived value, not an assigned registry number. The constructed code travels on every entry line from cargo release data through the entry summary.

This entry reflects the rule as of November 2026. The links in this article go to the primary documents: the CBP form instructions, the regulations and the official agency pages themselves. Read the source.

At a glance

• Full name: Manufacturer Identification code (MID) construction rule
• Who prepares or uses it: Customs brokers, importer self-filers and the importer's product master; read by CBP for targeting and verification
• When in the lifecycle: Before transmission, when entry line data is built from the commercial invoice
• System or channel: ACE via ABI, on entry and entry summary lines
• Governing authority: CBP Form 7501 (02/26) instructions; 19 CFR 102.23 for textiles
• Not to be confused with: a DUNS number or the ultimate consignee number
• Related terms: MID code, ACE AD/CVD case management, ACE Cargo Release, CATAIR Appendix B

Where does the MID construction rule come from?

MID construction is defined in the instructions to CBP Form 7501 (02/26), the entry summary form, which set out how filers derive a manufacturer's code from its name and address. Because the rule lives in the form instructions rather than in a registry, no one applies for an MID and CBP does not issue one. The filer builds it each time from the same inputs, which is why a disciplined, repeatable process matters more than any lookup. For background on what the finished code does on an entry line, see our MID code explainer.

How does MID construction work, element by element?

MID construction assembles four elements in a fixed order, all taken from the manufacturer's name and address as shown on the invoice.

Country

The code begins with the ISO country code of the country where the manufacturer is located, which is not necessarily the country of the seller or the shipper.

Name

Next come the first three characters of each of the first two words of the manufacturer's name. Articles and trade terms such as The, Company or Ltd are not treated as name words; follow the examples in the 7501 instructions for how such words are skipped.

Street address

Then come up to four numeric characters taken from the street address number of the manufacturing location. A post office box or suite number is not the street address number.

City

The code ends with the first three characters of the city. Spell the city the same way every time, or the same factory will produce two different codes.

The BRIEF-level rule above is the whole of what this article states. Do not apply exceptions beyond those in the CBP Form 7501 instructions; for unusual names or addresses, follow the worked examples in the instructions themselves.

Who is responsible for MID construction and when does it happen?

MID construction is performed by the filer, usually the customs broker or the importer's product master, before any data is transmitted to CBP. The broker reads the manufacturer's name and address from the commercial invoice and derives the code mechanically. Many importers store the constructed MID in their product or supplier master so every broker and every filing uses the identical value. The goal is deterministic: one factory, one code; two factories, two codes. Consistency matters because CBP targeting, AD/CVD suffix checks and textile verification all key on the MID, and an inconsistent code can make one supplier look like many, or many like one.

Common MID construction errors

MID construction errors usually come from small judgment slips that produce a code that looks valid but identifies the wrong entity.

• Counting articles and trade terms: treating The, Company or Ltd as one of the first two name words.
• Wrong address digits: using a post office box or suite number instead of the street address number.
• Inconsistent city spelling: spelling the city differently between filings, which yields different codes for the same factory.
• Wrong party: building the code from the seller or trading company rather than the manufacturer.

The cost is not usually a rejected transmission, because a mis-built code can still pass format checks. The cost shows up later as misdirected targeting, mismatches with AD/CVD company data, or textile verification questions that are harder to answer when the MID does not match the actual producer.

How MID construction interacts with other ACE and ABI terms

MID construction feeds the MID code (Manufacturer Identification code), the field required on every entry line that identifies the manufacturer or shipper; it is not a DUNS number and not a supplier account number.

AD/CVD and textiles

ACE AD/CVD case management, the ACE function and public ADCVD Search through which CBP publishes Commerce case numbers and company suffixes, is where an inconsistent MID causes friction: the manufacturer on the line should match the company the case data describes (see our AD/CVD case management article). For textiles, 19 CFR 102.23 ties origin to the manufacturer, so the MID should reflect the origin-conferring manufacturer.

Release, in-bond and manifest

ACE Cargo Release, the ACE transaction through which the broker transmits the data CBP needs to decide release, carries the MID, and CBP answers with disposition codes (ACE cargo release disposition codes) such as a 1C release (disposition code 1C, meaning CBP has released the entry). A correct MID does not guarantee release, but a wrong one can feed targeting that leads to holds. MIDs are an entry data element, not part of the ACE truck eManifest (the electronic truck manifest highway carriers transmit before arrival) or ACE in-bond (the electronic system for moving unentered merchandise under bond), though those filings often precede the entry that carries the MID.

Reconciliation, code tables and support

ACE reconciliation (entry type 09) closes flagged value, classification, 9802 or FTA issues; it is not a tool for rebuilding mis-constructed MIDs, so confirm the correct correction path with CBP. CATAIR Appendix B (Valid Codes) holds code tables used across ABI transactions; confirm field formats in the current ACE ABI CATAIR. Your ABI client rep (ABI client representative, the CBP Office of Trade contact for your ACE connectivity and certification) can help with transmission questions about the MID field.

Frequently asked questions

Is MID construction the same as registering a manufacturer with CBP?

No. MID construction derives the code from the manufacturer's name and address under the CBP Form 7501 instructions; there is no registry and no assigned number.

Should MID construction use the seller's or the manufacturer's details?

MID construction uses the manufacturer's name and address. Building the code from the seller or a trading company is one of the most common errors.

Can a DUNS number or ultimate consignee number replace MID construction?

No. MID construction produces a distinct code; it is not a DUNS number and not the ultimate consignee number.

What if a manufacturer's name or address does not fit the MID construction rule neatly?

Follow the examples in the CBP Form 7501 instructions and do not invent exceptions. If the instructions do not resolve the case, confirm with CBP.

What importers and brokers should do

1. Store one constructed MID per factory in the product or supplier master and require every filing to use it.
2. Capture the manufacturer's street address number and standard city spelling at supplier onboarding, not from the seller's invoice header.
3. Audit existing MIDs for counted articles or trade terms, post office box or suite digits, and duplicate codes for the same factory.
4. For textiles and AD/CVD lines, confirm the MID identifies the producing manufacturer before transmission (see ACE Cargo Release).

Key references

• CBP forms page: source for CBP Form 7501 (02/26) and its instructions, including the manufacturer ID construction rule.
• 19 CFR 102.23: regulation on textile and apparel origin relevant to identifying the manufacturer.
• CBP AD/CVD page: CBP's antidumping and countervailing duty program information and ADCVD Search access.
• CBP ACE and automated systems: landing page for ACE and the ABI CATAIR.