The short answer: USDB held in Wallet of Satoshi can earn Bitcoin rewards at an annual rate of 3.5% to 6%, paid daily in BTC. The exact rate depends on your 24-hour trading volume. It is technically not interest. Wallet of Satoshi does not pay it. The rewards are a discretionary, promotional benefit funded by Flashnet, and they can be reduced, suspended, or discontinued at any time.
If you hold USDB and do nothing else, you earn the base rate of 3.5% per year.
Who pays what: USDB, Brale, Flashnet, and Wallet of Satoshi
Four different parties are involved, and mixing them up is the most common source of confusion.
- Brale issues USDB. It is a US-regulated stablecoin issuer, and USDB is backed 1:1 by T-bills and cash equivalents held at regulated custodians.
- Flashnet operates the protocol on Spark. It does not issue USDB and never touches the reserves. It funds the BTC rewards from its own revenue.
- Wallet of Satoshi is the wallet app. It lets you hold, send, receive, and swap USDB where available, but it pays nothing itself. Its own disclosure states the rewards are “not interest or yield paid by any stablecoin issuer.”
- Spark (by LightSpark) is the Bitcoin Layer 2 network USDB runs on, and the network your daily BTC payouts land in.
So: your dollars sit in USDB (Brale), your rewards come from Flashnet, and Wallet of Satoshi is the window you look through. 
How much you earn: the reward tiers
Your annual reward rate is set by your 24-hour trading volume on a rolling basis:
| 24-hour volume | Annual reward rate |
|---|---|
| $0 | 3.5% |
| $500+ | 4.0% |
| $2,500+ | 4.5% |
| $5,000+ | 5.0% |
| $10,000+ | 5.5% |
| $25,000+ | 6.0% |
No staking is required. You can trade or transfer your USDB freely and keep earning. Volume is measured in rolling 24-hour windows, so your rate can move up or down as trades enter or leave the window.
What that means in sats
Flashnet publishes these worked examples, assuming BTC at $100,000 and a constant balance and rate:
| USDB balance (rate) | Per day | Per month |
|---|---|---|
| 1,000 (3.5%) | 96 sats | 2,877 sats |
| 1,000 (4.0%) | 110 sats | 3,288 sats |
| 10,000 (3.5%) | 959 sats | 28,767 sats |
| 10,000 (4.5%) | 1,233 sats | 36,986 sats |
| 50,000 (5.0%) | 6,849 sats | 205,479 sats |
| 100,000 (6.0%) | 16,438 sats | 493,151 sats |
The payout is fixed in dollar terms and converted to BTC at the current exchange rate. When the BTC price is lower, you receive more sats for the same reward, and vice versa.
How the daily payout is calculated
- Minimum balance: 10 USDB. Below that, no rewards.
- Maximum rewarded balance: 500,000 USDB. Holdings above that earn nothing extra.
- Payout time: daily at 01:00 UTC, in BTC, to your Spark wallet.
- Balance method: Flashnet uses your time-weighted average balance (TWAB), not a snapshot. If you hold 1,000 USDB for 12 hours and 2,000 USDB for the next 12, your TWAB is 1,500 USDB. Depositing right before the cutoff only counts for the time it was held, so there is no way to game the payout.
Why it is not really “interest”
Wallet of Satoshi’s disclosure document is explicit on this point. The Bitcoin rewards are a discretionary promotional benefit provided and funded by Flashnet. They are not interest or yield paid by the stablecoin issuer, they are variable, they are not guaranteed, and they may be reduced, suspended, or discontinued at any time. You are also responsible for any tax obligations on rewards received.
That distinction matters. Interest implies a contractual obligation to pay. These rewards are closer to a cashback program funded out of Flashnet’s protocol revenue, and Flashnet’s own transparency page frames them exactly that way: a growth investment paid from revenue, with no rehypothecation, no lending, and no fractional reserves. If Flashnet’s revenue falls, the rewards can fall with it.
The risks, plainly stated
- De-peg risk. USDB aims to hold $1 but is not guaranteed to. Its value depends on Brale’s solvency and reserves.
- Issuer controls. As a regulated issuer, Brale can freeze, block, seize, or burn USDB to comply with law or sanctions. Wallet of Satoshi cannot prevent or reverse that.
- No WoS redemption. Wallet of Satoshi does not redeem USDB for fiat. Par redemption is Brale’s obligation alone and may require a direct relationship with Brale.
- Availability. Stablecoin features and the rewards program are limited to supported jurisdictions and can be restricted or withdrawn.
- Self-custody responsibility. In WoS, USDB is held in the self-custody Spark account under your exclusive control. Lose your keys and the funds are gone, rewards included.
How to start earning
- Get USDB into a Spark wallet. Inside Wallet of Satoshi, you can swap BTC for USDB via Flashnet at market rates, where the feature is available in your region.
- Hold at least 10 USDB.
- Rewards accrue automatically and land daily in BTC. Trading is optional; the base 3.5% applies with zero volume.
FAQ
Does Wallet of Satoshi pay interest on USDB?
No. Wallet of Satoshi pays nothing. BTC rewards on USDB balances are funded by Flashnet, a third party.
What is the USDB reward rate?
3.5% to 6% per year, paid daily in BTC. The base rate with no trading volume is 3.5%.
What is the minimum USDB balance to earn rewards?
10 USDB.
Are USDB rewards guaranteed?
No. They are discretionary and promotional. Flashnet can reduce, suspend, or discontinue them at any time.
Is USDB safe?
USDB is issued by the regulated issuer Brale and backed 1:1 by T-bills and cash equivalents, but it is not FDIC insured, it can de-peg, and the issuer can freeze funds for legal compliance.
Do I need to stake or lock my USDB?
No. Rewards accrue on your balance with no staking and no lockup.
Sources
- Flashnet USDB rewards documentation: https://docs.flashnet.xyz/usdb/rewards
- Flashnet USDB transparency page: https://docs.flashnet.xyz/usdb/transparency
- Wallet of Satoshi Disclosure Document v1.23 (updated 25 August 2026), Section 8: https://www.walletofsatoshi.com/disclosure
