# Soulbound tokens: transfer restrictions and issuer powers

“Soulbound token” commonly describes a token designed to be non-transferable. ERC-5192 provides a minimal interface for reporting whether an NFT is locked and requires transfers to fail while locked. It does not by itself prove a person’s identity or define a complete issuance, revocation, privacy or recovery system.

Evidence: [Minimal Soulbound NFTs](https://eips.ethereum.org/EIPS/eip-5192)

Canonical: https://degreesofsatoshi.com/encyclopedia/soulbound-tokens/
Published: 2026-10-02
Substantively modified: 2026-10-02
Independently verified by an automated reviewer: 2026-10-02T18:12:41.505Z
Data current through: 2026-10-02

AI-assisted research and drafting with a separate automated source-verification pass; no external expert or named human review is implied.

## Key facts

- **Signal:** locked(tokenId) reports whether the specified token is locked. ([Minimal Soulbound NFTs](https://eips.ethereum.org/EIPS/eip-5192))
- **Transfer rule:** ERC-721 functions that transfer the token between accounts must fail while it is locked. ([Minimal Soulbound NFTs](https://eips.ethereum.org/EIPS/eip-5192))
- **Scope:** The standard is a minimal extension, not a universal credential policy. ([Minimal Soulbound NFTs](https://eips.ethereum.org/EIPS/eip-5192))

## A token can represent an issuer’s assertion

A project might use a non-transferable token to represent course completion or membership. The contract can restrict transfer, but the value of the assertion still depends on who issued it and how eligibility was checked.

A blockchain account is not automatically one person. Preventing the token’s transfer does not prove exclusive control of the account’s signing authority.

Evidence: [Minimal Soulbound NFTs](https://eips.ethereum.org/EIPS/eip-5192)

## Ask about revocation and account loss separately

Different implementations may add expiration, burning, revocation or migration policies. The minimal locked interface does not make these policies uniform.

A reader evaluating a credential should identify what happens after a mistake, a compromised key or the issuer’s closure. The “soulbound” label is not a recovery plan.

Evidence: [Minimal Soulbound NFTs](https://eips.ethereum.org/EIPS/eip-5192)

## Non-transferability does not make a public claim private

If a token and its ownership are publicly inspectable, others can associate the credential with that account. Metadata may disclose additional information.

Evaluate what is published and whether the subject consented to that disclosure. Transfer restrictions and privacy are different properties.

Evidence: [Minimal Soulbound NFTs](https://eips.ethereum.org/EIPS/eip-5192); [Non-Fungible Token Standard](https://eips.ethereum.org/EIPS/eip-721)

## Questions

### Does a soulbound token prove that an account belongs to one unique human?

No. The transfer restriction alone does not establish uniqueness, identity or the process used to issue the claim. Those require separate evidence and mechanisms.

Evidence: [Minimal Soulbound NFTs](https://eips.ethereum.org/EIPS/eip-5192)

## Claims and scope

### soulbound-tokens-quick-answer

“Soulbound token” commonly describes a token designed to be non-transferable. ERC-5192 provides a minimal interface for reporting whether an NFT is locked and requires transfers to fail while locked. It does not by itself prove a person’s identity or define a complete issuance, revocation, privacy or recovery system.

Scope: {"collection":"ethereum","dataAsOf":"2026-10-02","blockHeight":null}

### soulbound-tokens-fact-signal

Signal: locked(tokenId) reports whether the specified token is locked.

Scope: {"collection":"ethereum","dataAsOf":"2026-10-02","blockHeight":null}

### soulbound-tokens-fact-transfer-rule

Transfer rule: ERC-721 functions that transfer the token between accounts must fail while it is locked.

Scope: {"collection":"ethereum","dataAsOf":"2026-10-02","blockHeight":null}

### soulbound-tokens-fact-scope

Scope: The standard is a minimal extension, not a universal credential policy.

Scope: {"collection":"ethereum","dataAsOf":"2026-10-02","blockHeight":null}

## Sources

- [Minimal Soulbound NFTs](https://eips.ethereum.org/EIPS/eip-5192) — Ethereum Improvement Proposals. A minimal locked-token interface; not a universal identity or revocation design. Locator: Specification. Retrieved: 2026-10-02T17:03:42.322Z.
- [Non-Fungible Token Standard](https://eips.ethereum.org/EIPS/eip-721) — Ethereum Improvement Proposals. Optional token metadata interfaces and the distinction between token and external resource. Locator: Specification: ERC721Metadata; Metadata Choices (metadata extension); NFT Identifiers. Retrieved: 2026-10-02T17:03:42.309Z.

## Revision history

- 2026-10-02: First publication after primary-source research and independent automated verification.

## Cite this entry

Degrees of Satoshi editorial project. “Soulbound tokens: transfer restrictions and issuer powers.” Published 2026-10-02; updated 2026-10-02. https://degreesofsatoshi.com/encyclopedia/soulbound-tokens/