ERC-3475, “Abstract Storage Bonds”, is a token standard designed for debt instruments. One contract can manage many bond classes, each with many issuances (nonces), and each class and nonce can carry its own on-chain metadata — coupon, maturity, collateral, redemption conditions. Instead of deploying a new ERC-20 for every bond series, an issuer can run an entire debt programme from one contract, with redemption progress and terms queryable on-chain.
Key takeaways
- Class = a type of bond (e.g. 5-year senior secured notes); nonce = a specific issuance of that class (e.g. the March 2026 tranche).
- Balances are tracked per
(account, classId, nonceId); transfers can include multiple class/nonce pairs in one transaction. - Metadata is stored abstractly on-chain, so new instrument types can be described without changing the contract.
- Useful for debt programmes with many series; for regulated distribution add identity-gated transfers.
How ERC-3475 works
| Concept | Role |
|---|---|
Transaction{classId, nonceId, amount} |
Unit of a transfer, issuance, redemption or burn |
transferFrom(from, to, Transaction[]) |
Move several bond positions at once |
issue(to, Transaction[]) |
Create bonds for an investor |
redeem(from, Transaction[]) |
Redeem matured bonds |
burn(from, Transaction[]) |
Cancel bonds |
classMetadata / nonceMetadata |
Descriptions of fields (title, type) |
classValues / nonceValues |
The actual term values per class and issuance |
getProgress(classId, nonceId) |
How far a bond is towards redemption |
Use cases
- Corporate debt programmes — many series under one framework, each a nonce.
- Private credit notes — pools or vintages as classes; drawdowns as nonces. See our private credit guide and the education loan case study.
- Amortising instruments — progress tracking for principal repayment.
- Debt-instrument marketplaces — we have built issuance and trading platforms for debt instruments where class/nonce structures simplify listings.
Strengths and trade-offs
Strengths - One contract, many instruments — fewer deployments and audits. - Rich, queryable terms on-chain for investors and venues. - Batch transfers across series.
Trade-offs - Less wallet and exchange support than ERC-20 or ERC-1155. - No built-in compliance, identity or agent controls. - On-chain metadata costs gas and must not include confidential terms.
ERC-3475 vs other debt designs
| Design | Best when |
|---|---|
| ERC-3475 | Many series under one programme with structured on-chain terms |
| ERC-3525 | Positions need partial transfers and merging by value |
| ERC-3643 per series | Regulated distribution with strong identity requirements |
| ERC-1155 IDs per series | You also need non-debt assets in the same contract |
Example class and nonce layout for a debt programme
| Class ID | Class metadata | Nonce ID | Nonce values |
|---|---|---|---|
| 1 | Senior secured notes, 6.5% coupon, EUR | 1 | Issue 2026-03-01, maturity 2029-03-01 |
| 1 | Senior secured notes, 6.5% coupon, EUR | 2 | Issue 2026-09-01, maturity 2029-09-01 |
| 2 | Subordinated notes, 9% coupon, EUR | 1 | Issue 2026-03-01, maturity 2031-03-01 |
| 3 | Trade-finance notes, 90-day, USD | 1…n | One nonce per weekly issuance |
Investors hold balances per (class, nonce). A single transfer can move positions across several classes and nonces — useful for portfolio sales between institutions.
Tracking redemption progress
getProgress(classId, nonceId) returns how far an issuance is towards redemption (for example time elapsed versus maturity). Front-ends use it to show investors maturity timelines; redemption contracts use it to decide when bonds can be redeemed.
Coupons and amortisation
- Bullet bonds: coupons paid per period; principal at maturity.
- Amortising notes: principal repaid in instalments; balances reduce via partial redemptions per nonce.
- Floating-rate notes: coupon rate updated each period from a benchmark oracle; record values per nonce.
Compliance and reporting
Add an eligibility layer that checks every Transaction in a transfer batch, and export registers per class and nonce for transfer agents and auditors. Keep confidential covenants off-chain, anchoring document hashes instead.
Frequently asked questions
It can be, if you add identity checks and agent controls around transfers. Many regulated issuances use ERC-3643 per series instead for ecosystem support.
A class defines a bond type and its shared terms; a nonce is a specific issuance of that class with its own dates and values.
Yes. A distribution contract can read balances per class and nonce and pay coupons pro-rata in a stablecoin or record entitlements for off-chain payment.
Yes, on any EVM-compatible chain.
Yes — any debt claim with defined terms can be modelled as a class with nonces for individual drawdowns or vintages.
It is stored and typed on-chain per class and nonce, rather than as off-chain JSON per token.
NUVZ is the RWA and Web3 engineering brand of ESS ENN Associates (est. 1993). Our team has designed and shipped tokenization platforms for real estate, education loans, solar PPAs, energy, carbon credits, bank deposits and trade documents. About us · Case studies
This article is for general information only and is not legal, tax or investment advice. Token standards evolve — always confirm the current status of an ERC at eips.ethereum.org and take advice from qualified counsel in each jurisdiction before issuing tokens.
