# USD0 Savings (sUSD0) sUSD0 is the savings token for USD0, implemented as a **non-rebasing ERC-4626 vault**. It turns USD0 from a settlement stablecoin into a yield-accruing savings instrument that is **composable, transparent, and fully on-chain**. Users deposit USD0 into a permissionless vault and receive sUSD0 shares in return. **sUSD0 balances do not rebase**; instead, value accrues through an **exchange rate that increases over time**. As a result, redeeming sUSD0 returns **more USD0 than initially deposited** (assuming positive yield over the holding period). Yield originates from the protocol’s underlying collateral stack, sovereign US Treasury Bills and other short-term yield-bearing assets, and is passed through to sUSD0 holders via the vault’s exchange-rate mechanism. *** ## Key Facts * **Underlying asset:** USD0, the RWA-backed stablecoin at the core of Usual Protocol * **Standard:** ERC-4626 vault (**non-rebasing**, accrual via exchange rate) * **Access:** Permissionless; no KYC/KYB requirement * **Yield source:** Sovereign T-Bills and overnight reverse repos backing USD0 collateral * **Yield distribution:** Controlled via on-chain parameters; the rate may vary with market conditions and DAO decisions * **Redemption math:** `USD0 out = sUSD0 × exchangeRate` (*t* ≥ 1) * **Contract address (Ethereum):** `0xd861bE82dEe3223CFBEd160791f6550b0704D406` *** ## How sUSD0 Works 1. **Deposit** USD0 into the sUSD0 ERC-4626 vault. 2. **Receive** sUSD0 shares representing a proportional claim on the vault’s total assets. 3. **Accrue yield passively** as the **sUSD0↔USD0 exchange rate increases** over time. 4. **Redeem anytime** to unwrap sUSD0 and receive USD0 at the current exchange rate. Because sUSD0 follows the ERC-4626 standard, it is straightforward to integrate across DeFi. Any protocol that supports ERC-4626 can generally support sUSD0 **without custom adapter logic**, simplifying accounting and composability. *** ## Yield Source and Collateral Stack The yield that accrues to sUSD0 traces back to the DAO revenue. ### How yield reaches sUSD0 holders The protocol captures yield generated by the underlying collateral and routes a portion of it to sUSD0 holders by increasing the vault’s **exchange rate** over time. Distribution parameters—including how much yield is allocated to sUSD0 and how quickly it accrues—are adjustable via **USUAL governance**. *** ## sUSD0 vs. USD0 (At a Glance) | Feature | USD0 | sUSD0 | | ------------------ | ----------------------------- | -------------------------------------- | | **Purpose** | Settlement asset | Savings instrument | | **Value behavior** | Pegged 1:1 to USD | Grows via exchange rate | | **Access** | Free mint / redemption | Wrap / unwrap via ERC-4626 vault | | **Use cases** | Payments, collateral, trading | Yield generation, DeFi integration | | **Design** | Rebase-free stablecoin | ERC-4626 wrapper (non-rebasing shares) | *** ## sUSD0 vs. the Bond Product (bUSD0) Usual Protocol offers two distinct ways to earn yield on USD0, each aligned to different risk profiles and time horizons: | Feature | sUSD0 | bUSD0 | | ---------------------- | ------------------------------------------- | ---------------------------------------------------- | | **Mechanism** | ERC-4626 vault; exchange-rate accrual | Liquid bond; daily USUAL token coupons | | **Lock-up** | None — deposit and withdraw freely (3bips) | Bond with maturity date (June 2028) | | **Yield denomination** | USD0 (real yield) | USUAL tokens (alpha yield) or Base Yield Guarantee | | **Yield type** | Predictable, T-Bill-based | Variable; dependent on USUAL token price | | **Early exit** | Instant redemption at current exchange rate | Secondary-market sale or recombination with rt-bUSD0 | | **DeFi composability** | High (ERC-4626 standard) | High (tradeable ERC-20; usable as collateral) | **sUSD0** is designed for users seeking **stable, predictable yield** denominated in USD0, with no lock-up and no direct exposure to token price volatility. **bUSD0** is designed for users willing to commit capital for potentially higher returns driven by USUAL emissions and bond discount dynamics. *** ## Benefits * **Predictable yield:** Transparent accrual via a rising exchange rate, backed by sovereign instruments * **Stable collateral base:** Short-duration sovereign exposure (portfolio average duration **< 0.33 years**) * **Non-rebasing design:** DeFi-friendly for pools, lending markets, and integrations that prefer fixed balances * **Permissionless access:** Fully on-chain deposit and redemption—no intermediaries * **Governance-aligned:** Yield distribution parameters adjustable via USUAL governance * **Real yield in USD0:** Returns are denominated in USD0 and sourced from real-world fixed-income instruments (not primarily token emissions) *** ## Rebasing Track USD0 also supports a **rebasing mode**, where yield is distributed directly to **USD0 balances** at the “cash layer.” This is part of Savings but lives on USD0 itself (not as a separate token). It is suitable for applications that prefer native balance growth over ERC-4626 wrappers, for example, wallets or payment interfaces where users expect their USD0 balance to increase automatically without wrapping into a vault token. *** ## Contract Information | Contract | Address (Ethereum) | | --------------------- | -------------------------------------------- | | **sUSD0** | `0xd861bE82dEe3223CFBEd160791f6550b0704D406` | | **USD0 (underlying)** | `0x73A15FeD60Bf67631dC6cd7Bc5B6e8da8190aCF5` | --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.usual.money/usual-products/yield-products/usd-products/usd0-savings.md?ask= ``` The question should be specific, self-contained, and written in natural language. 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