T-bill rate on stablecoin balances: how fintechs pay it

A fintech can pay customers a T-bill rate on their USDC through a vault that holds a tokenized money market fund. The vault's USDC buffer keeps withdrawals open at weekends.

On 15 September 2026 the US Senate failed to advance the CLARITY Act, 49 votes to 50. The GENIUS Act's rule stays in place: stablecoin issuers can't pay holders yield. A fintech, wallet or exchange that wants to pay a T-bill rate on stablecoin balances around the clock builds a separate product in three layers: a tokenized money market fund such as BlackRock's BUIDL, Circle's USYC or WisdomTree's WTGXX, a vault from a provider such as Upshift that holds the fund shares next to a USDC buffer, and the app's Earn tab.

The fund earns the Treasury income, and the buffer pays withdrawals at weekends. The 13-week Treasury bill yielded 4.11% (coupon-equivalent) on 2 October 2026, according to the US Treasury's daily bill rates. Customers see a USDC balance that grows daily, at less than that rate once the fund, the vault and the app take their fees and the buffer sits idle.

The building blocks run from T-bills up to the Earn tab

In the diagram, a customer's USDC moves from the Earn tab into the vault, which buys fund shares with most of it and keeps the rest as USDC. Treasury income flows back up into the fund shares every day. When a customer withdraws on a Saturday, the buffer pays them, and on Monday the vault redeems some fund shares to fill the buffer back up.

A tokenized fund supplies the T-bill income

Tokenized Treasury funds held $14.82 billion on 4 October 2026, and their 7-day average yield was 3.66%, according to rwa.xyz's Treasury dashboard. Circle's USYC page limits the fund to non-US persons from $100,000, with near-instant USDC redemptions up to a capacity limit and T+0 or T+1 settlement above it.

BUIDL took US qualified purchasers with a $5,000,000 minimum on 23 September 2026, and WTGXX took US investors from $1 (rwa.xyz asset pages). On 24 February 2026 the SEC let WisdomTree's dealer trade WTGXX shares at $1 around the clock, settled in USDC, starting with institutional users on WisdomTree Connect, CoinDesk reported.

A vault leaves those eligibility rules in place. The issuer approves the vault once as a holder, and customers hold the vault's receipt token, yet US rules look through a vehicle built to invest in a qualified-purchaser fund to its depositors. Customer vaults use funds open to those customers, such as USYC for non-US holders, or serve customers outside the US. BUIDL vs USYC vs BENJI compares the funds side by side, and the tokenized treasuries guide lists exit routes for the six largest.

The vault holds the fund next to a USDC buffer

The buffer makes the rate 24/7. Fund redemptions follow business days and cut-off times. Customers withdraw on Sunday nights and public holidays. A vault keeping, say, 10% of its assets in USDC can pay those withdrawals straight away. It then refills the buffer in large amounts, through the fund's own 24/7 USDC route where one exists (BUIDL through Circle, USYC, OUSG) or the fund's next daily redemption. A payments app that pays out every hour keeps more in USDC than a savings product where balances sit for months. A bigger buffer pays out faster and earns less, because USDC sitting in the buffer earns nothing.

A qualifying fintech could hold the fund itself, and some funds pay USDC around the clock. The vault does its work on customer balances, where many people hold small amounts:

The vault adds its own smart contract and oracle risk, and the buffer trims the rate a little. BUIDL vs USYC vs BENJI compares the funds themselves.

When a withdrawal is larger than the buffer, the vault can use the fund's instant route while that route has capacity, wait for the fund's normal redemption window, or sell fund shares for USDC in one transaction through Upshift Clear, a pool funded by liquidity providers that pays an oracle price and settles with the issuer later. Upshift processes claimable redemptions on all its vaults daily. Each vault has its own withdrawal lag, and most offer instant redemption for a fee, subject to available liquidity.

Where the vault runs on the Upshift prime stack, a policy engine limits what the vault can touch by chain, protocol, token and contract function. A mandate of "tokenized government funds and USDC only" is enforced by the contracts, and a transaction outside it reverts. Upshift's multi-oracle engine prices each position for the vault's net asset value (NAV), and the curator has no say in its own mark.

The customer sees a USDC balance that grows every day

On the Earn screen, a customer deposits USDC and sees a balance in dollars. Behind it they hold vault shares, and the app multiplies the share count by the share price to show the balance. The fund's income lifts the share price. The balance creeps up each day, and there's no payout to claim. Funds pay income in different ways (BUIDL adds new tokens at $1, other funds raise their token price), and the vault turns all of them into one rising share price.

On the screen itself, the fintech labels four things:

• The rate label. A 30-day trailing rate can be shown as simple annualised or compounded, and the two differ by a few basis points. Say which one it is and that it varies.
• Withdrawal timing. Show whether a withdrawal clears instantly from the buffer, with any instant-redemption fee, or goes into the daily queue.
• What the customer holds: vault shares backed by fund shares and USDC, with no deposit insurance.
• Where the rate comes from, in plain words such as "short-term US Treasury bills held through a tokenized fund".

Tria built its Earn product on the Upshift SDK (npm package @augustdigital/sdk), which handles deposits, withdrawals and share balances for EVM chains, Solana and Stellar through one client. Fordefi Earn listed Upshift vaults, including earnAUSD and two Sentora vaults, on 8 September 2026.

The rate passes through after three deductions

A customer's rate is the fund's yield minus the cost of the buffer, the vault's fees and the fintech's own share. The worked example uses the rwa.xyz 7-day average for the fund. The other three lines are illustrative, since each vault and fintech sets its own.

On a $10 million book of customer balances, the fintech's 0.50% share comes to about $50,000 a year. The customer rate moves with US short rates in both directions. The T-bill calculator runs the same sum at other rates and holding periods. Upshift sets management and performance fees per vault, and on most vaults a management fee change goes through a timelock before it applies.

The GENIUS Act bars issuers from paying yield

Section 4(a)(11) of the GENIUS Act, signed on 18 July 2025, bars permitted payment stablecoin issuers from paying holders "any form of interest or yield ... solely in connection with the holding, use, or retention" of the stablecoin. Section 20 sets the Act's start date at 18 January 2027, or 120 days after regulators issue final rules if that comes sooner.

The OCC proposed its implementing rule on 25 February 2026. It presumes a breach where an issuer pays an affiliate or "related third party" that in turn pays the issuer's holders, according to Sullivan & Cromwell's summary.

The CLARITY Act would have gone further. Its final Senate text barred crypto firms from paying yield "economically or functionally equivalent" to bank deposits while keeping rewards tied to payments and trading. Cloture failed 49-50 on 15 September 2026, and no new vote was scheduled as of 4 October 2026 (CoinDesk, DeFi Rate).

Platforms pay customers on stablecoins in two ways today. PayPal pays 4% rewards on PYUSD held in its app, at a rate PayPal sets and can change (PayPal's PYUSD page, 4 October 2026). A T-bill vault works differently: the customer swaps USDC for vault shares, and the return comes from fund shares the vault holds and floats with them.

In the EU, Article 50 of MiCA bars e-money token issuers and crypto-asset service providers from granting interest on e-money tokens. Applying any of these rules to a given Earn design is work for the fintech's counsel. This section is our synthesis of the sources, not legal advice. How the GENIUS and CLARITY Acts reshape stablecoin yield goes through the rules in more depth.

Each layer adds its own risk

• Fund and issuer: the manager, custodian and transfer agent behind each fund, and terms the issuer can change.
• Redemption timing: a very large outflow can outrun the buffer and the instant facility and wait on the fund window.
• Rate cuts, which pass straight through to the customer rate.
• Smart contracts and oracles in the vault and any instant facility.
• Eligibility: many funds are closed to US or retail investors, which limits which funds a given vault can hold.

Upshift's contracts have been through 11 smart contract audits by 6 independent firms, and each vault's owner is a Gnosis Safe multisig. Upshift carries no protocol-level smart contract insurance; cover can be bought from third-party providers. Vault provider due diligence lists the questions fintechs put to a provider before integrating.

Always make sure to do your own research and be aware of the above and any other risks before depositing.

Core and Enhanced bands run on the same integration

Upshift is onchain yield infrastructure for fintechs and asset managers with stablecoin balances. Platforms usually open Earn with the Conservative band and add higher bands once the first has a track record, using the same SDK calls with a different vault address. The indicative bands on the Upshift yield options page, before vault fees and with no return guaranteed:

• Conservative (3-4%): tokenized Treasury and money market funds, earning the 24/7 T-bill rate.
• Core (5-7%): diversified lending and tokenized credit. Sentora USD, a USDC vault managed by Sentora, held $94.4 million and returned about 7.2% annualised over the trailing 30 days (Upshift API, 4 October 2026).
• Enhanced (8%+): market-neutral strategies and looped carry, with capacity caps and longer withdrawal windows.

Each band is its own vault with its own disclosures and due diligence. Tiered stablecoin yield covers how platforms price a menu, and tiering vault strategies by risk covers which strategies go in which band. For a platform that rules out lending protocols altogether, stablecoin yield without DeFi sets out the options. A vault can be open, limited to an allow list or reserved for one depositor, and Vault-as-a-Service covers vaults launched for a single platform.

Frequently asked questions

How can a fintech offer a 24/7 T-bill rate on customer stablecoin balances?

By routing customer USDC into a vault that holds tokenized money market fund shares, such as BUIDL, USYC or WTGXX, plus a USDC buffer. The buffer pays withdrawals at any hour and refills from fund redemptions on business days. The fintech integrates the vault into its Earn tab through an SDK or API.

How can we offer stablecoin yield without DeFi exposure?

Limit the vault's mandate to tokenized Treasury and money market funds and USDC. On Upshift vaults run through the prime stack, the policy engine enforces that limit in the contracts. An offchain lending facility to vetted institutional borrowers is a second option that stays clear of lending protocols, with borrower credit risk in place of fund risk.

What risk tiers should a fintech offer, from T-bills to lending to credit?

Upshift groups vaults into Conservative (tokenized T-bills, indicative 3-4%), Core (lending and tokenized credit, 5-7%) and Enhanced (market-neutral and looped carry, 8%+). Platforms usually launch with one Conservative vault and add Core once that vault has a track record.

Do tokenized money market funds redeem on weekends?

Standard redemptions follow business days. Some funds add round-the-clock routes: Circle's USYC offers near-instant USDC redemptions up to a capacity limit, and WisdomTree won SEC relief on 24 February 2026 for 24/7 dealer trading in WTGXX. A vault's USDC buffer covers weekend withdrawals for any fund it holds.

What rate do customers get after fees?

Less than the T-bill rate. With tokenized Treasury funds averaging 3.66% (rwa.xyz, 4 October 2026), a 10% buffer, a 0.25% vault fee and a 0.50% fintech share leave about 2.5%. The rate falls when the Federal Reserve cuts.

Can a stablecoin issuer pay the T-bill rate directly?

Not in the US. The GENIUS Act bars permitted payment stablecoin issuers from paying holders interest or yield, and the OCC's February 2026 proposal presumes a breach where an issuer routes yield to holders through an affiliate or related third party.

Keep reading

• Tokenized money market funds vs stablecoin vaults. Eligibility, minimums and exit times compared.
• How exchanges build an Earn product. Who pays the yield in each model.
• How neobanks and fintechs offer stablecoin yield. The business models behind an Earn launch.
• Embedded yield. How apps distribute vaults to their users.