ERC-3643 and ERC-1400 are standards for tokens that represent securities, and the practical difference lies in controlling who can be a holder. ERC-3643 incorporates on-chain identity and eligibility rules executed by the contract itself, which fits issuances where the investor must be verified before each transfer.
Your technical team is debating which standard to use for the token. Someone proposes ERC-3643. Someone else argues for ERC-1400. And no one is sure what that choice implies for complying with Spanish law. It is an architecture decision that carries consequences throughout the entire life of the issuance: how you control who can hold the security, how you block wallets, how you separate classes of shares, how you prove to the CNMV (National Securities Market Commission) that you comply.
Here we compare the two most widely used technical standards for regulated security tokens (security tokens) on Ethereum: ERC-3643 and ERC-1400. What each one solves, how they differ and how they fit with the Spanish legal framework. A warning from the start: the standard is the technical layer. The law rules. The standard only has to let you comply with what the law requires.
Which standard to choose, in one sentence
If you want integrated on-chain identity and compliance verified on every transfer, ERC-3643 gives you more out of the box; if you need to separate several classes of security in the same contract and tie legal documents to the token, the ERC-1400 family gives you that granularity. Neither of the two makes you comply with the law: that is done by the LMVSI and the ERIR.
The LMVSI is Ley 6/2023 de los Mercados de Valores y de los Servicios de Inversión. The ERIR is the Entity Responsible for Registration and Registry, the figure that keeps the ownership record of your blockchain-represented security (art. 8 LMVSI). The technical standard lives below all of that.
What is ERC-3643 (T-REX)
ERC-3643 is a “permissioned token” standard that puts investor identity inside the contract itself: only wallets that meet predefined conditions can hold the token.
T-REX stands for Token for Regulated EXchanges. It is a suite of open-source smart contracts for issuing, managing and transferring permissioned tokens. It reached “Final” status as an EIP (Ethereum Improvement Proposal) on December 15, 2023. It was the first EVM-compatible tokenization standard approved by the Ethereum community. It is maintained by the ERC3643 Association, with members such as Apex Group, Invesco or Polygon.
How it works
The central piece is ONCHAINID, a decentralized identity framework on-chain. Each investor has an on-chain identity with their verified credentials (KYC, accreditation, jurisdiction). The token checks two things on every transfer: the investor rules (via ONCHAINID) and the issuance rules. If both are met, the transfer goes through. If not, it is rejected in the contract itself.
Out of the box it supports whitelisting (only KYC-verified wallets), token and wallet freezing, and forcing operations by an authorized agent. Compliance is modular: you add rule modules (country limits, maximum number of investors, lock-up periods) without rewriting the token.
What it means for you: if your issuance needs to control identity and transfer restrictions with little custom logic, ERC-3643 saves you work. Reusable identity across issuances is its great operational advantage.
What is ERC-1400 (Security Token Standard family)
ERC-1400 is not a single contract: it is a family of standards that distributes the functions of the regulated security across several pieces that fit together.
It was promoted by Polymath (authors such as Adam Dossa) as Security Token Standard. Unlike ERC-3643, ERC-1400 did not reach “Final” status as an EIP; it is a widely adopted community standard but formally in draft. It is made up of several sub-standards:
The pieces of the family
- ERC-1410 (partitions): enables “partial fungibility.” It divides the balance into partitions or tranches within the same contract. It serves to separate classes of security: locked versus liquid shares, different series, lots with different conditions.
- ERC-1594 (core): the core of transfer restrictions. It validates each transfer before executing it and returns reason codes if it rejects it, which helps justify why an operation did not go through.
- ERC-1643 (documents): ties legal documentation to the token. It stores the document hash on-chain (to prove it has not been altered) and a link to the off-chain document.
- ERC-1644 (controller operations): gives an authority the ability to force transfers between addresses. Useful for court orders, fraud, or loss of private keys.
What it means for you: if your security has several classes or series, or you need to anchor the prospectus and agreements to the token itself, the ERC-1400 family gives you that structure. In exchange, you build the identity and compliance logic yourself, because it does not come integrated as in ERC-3643.
ERC-3643 vs ERC-1400: comparison
The core difference: ERC-3643 brings identity and compliance built in; ERC-1400 gives you modular building blocks to build the security's behavior, with more class flexibility but more integration work.
| Dimension | ERC-3643 (T-REX) | ERC-1400 (Security Token Standard) |
|---|---|---|
| Identity / KYC | ONCHAINID integrated on-chain; reusable identity | Not integrated; you add it with external systems or your own modules |
| Transfer control | Investor rules + issuance rules checked on every transfer | Validation via ERC-1594 with reason codes |
| Partitions / classes | Not native; modeled with modules or multiple tokens | Native via ERC-1410 (partial fungibility) |
| Legal documents | Not native in the standard | Native via ERC-1643 (on-chain hash + link) |
| Enforce compliance | Authorized agent: freeze, force, recover | Controller operations via ERC-1644 |
| Standard status | EIP «Final» (Dec 2023) | Community draft, widely adopted |
| Adoption | Association with institutional backing; focus on RWA | Broad across security token platforms |
| Legal fit (Spain) | Depends on the issuance; both must support what the LMVSI requires | Depends on the issuance; both must support what the LMVSI requires |
Both cover the essentials of a regulated security: whitelisting, transfers only to KYC-verified wallets, freezing, and the ability to enforce compliance. The choice is not «which one complies with the law», because neither complies on its own. It is «which one fits your issuance and your stack better».
The standard does not replace the legal framework
Legal compliance for your security token in Spain is not provided by the technical standard: it is provided by the LMVSI and the ERIR regime. The standard only has to let you execute what the law requires you to control.
Your security represented through systems based on distributed ledger technology needs an ERIR that keeps the ownership register with full legal effect (art. 8 LMVSI; RD 814/2023). As of 2026, the first entity authorized by the CNMV as an ERIR is Ursus-3 Capital. That legal layer exists above Ethereum and above the standard you choose.
The standard comes into play to support the restrictions that the issuance needs. AML regulations require you to identify the investor (Ley 10/2010 de prevención del blanqueo de capitales): your token must be able to restrict transfers to wallets with verified KYC. The issuance may carry transfer restrictions (lock-ups, limits by jurisdiction, maximum number of holders): the standard must allow you to encode them. If an authority orders the blocking or recovery of tokens, the standard must support that operation.
What it means for you: first you define with your legal counsel what restrictions the issuance imposes. Then you choose the standard that supports them with the least integration effort. Not the other way around. To frame the full flow, review how to issue a security token in Spain and what an ERIR is.
How to choose between ERC-3643 and ERC-1400
Decide based on the real needs of your issuance, not on the standard’s fashion: reusable identity and built-in compliance point to ERC-3643; multiple classes of security and documents tied to the token point to ERC-1400.
Signals that point to ERC-3643
- You want reusable on-chain identity across several issuances.
- You prefer modular compliance checked on every transfer, without building it from scratch.
- You value a standard with EIP “Final” status and institutional backing for RWA.
Signals that point to ERC-1400
- Your security has several classes, series or tranches that must coexist in one contract.
- You need to anchor the prospectus, agreements or legal documents to the token itself.
- Your platform or provider already works on this family.
What it means for you: there is no universal winner. There is a standard that fits your case better. What does not change is the legal obligation: the Spanish legal layer governs over the technical one. If you are still framing the project, start from what asset tokenization is before going down to the detail of the standard.
What to do now
- Define with your legal counsel the transfer and identity restrictions imposed by your issuance (LMVSI, Ley 10/2010).
- Confirm the issuance and registration flow in this guide on issuing security tokens in Spain.
- Understand the role of the ERIR in the ownership register before finalizing the architecture.
- Map each legal requirement to a specific capability of the standard (KYC, freezing, partitions, documents, forcing transfers).
- Check the technical and regulatory terms in the glossary.
Frequently asked questions
Does ERC-3643 or ERC-1400 comply with Spanish law on its own?
No. Neither complies with the law on its own. Legal compliance is provided by the LMVSI and the ERIR regime (art. 8 LMVSI; RD 814/2023). The standard only has to let you execute the restrictions required by law.
What is the main difference between ERC-3643 and ERC-1400?
ERC-3643 integrates investor identity on-chain (ONCHAINID) and checks compliance on every transfer. ERC-1400 is a family of modular standards that stands out in partitions (classes of security) and in tying legal documents to the token, but you add identity separately.
Can I separate classes of shares in the same token?
With ERC-1400 yes, natively, thanks to ERC-1410 (partial fungibility by partitions). With ERC-3643 you model the classes with modules or with several tokens, because partitions are not native to the standard.
Do both standards allow freezing or forcing transfers?
Yes. ERC-3643 manages it with an authorized agent that can freeze and force operations. ERC-1400 does it with controller operations via ERC-1644. In both cases it serves for court orders, fraud or lost keys.
Do I need an ERIR even if I use a standard with integrated compliance?
Yes. The ERIR is a legal figure that keeps the ownership register with legal effect (art. 8 LMVSI). It exists above the technical standard. As of 2026, Ursus-3 Capital is the first ERIR authorized by the CNMV.
Which standard has more formal backing?
ERC-3643 reached Final status as an EIP in December 2023. ERC-1400 is a widely adopted community standard, but it did not reach Final status in the EIP process. Formal backing does not decide for you: the fit with your issuance decides.
Notice
Informational content. It does not constitute legal, tax or investment advice. HokenFi is a software and infrastructure provider; it does not provide regulated services. Check the current version of the rules cited in the BOE and EUR-Lex.
Cited regulations
- Ley 6/2023, de 17 de marzo, de los Mercados de Valores y de los Servicios de Inversión (LMVSI), BOE-A-2023-7053 (art. 8).
- Real Decreto 814/2023, BOE-A-2023-22764 (ERIR regime and CNMV registries).
- Ley 10/2010, de 28 de abril, de prevención del blanqueo de capitales y de la financiación del terrorismo, BOE-A-2010-6737.
- ERC-3643 (T-REX): specification at eips.ethereum.org/EIPS/eip-3643.
- ERC-1400 and family (ERC-1410, ERC-1594, ERC-1643, ERC-1644): Security Token Standard, thesecuritytokenstandard.org.
