USDC Blacklist and USDT Freeze Functions Explained

By Owen Thurm Published November 6, 2026 5 min read

Quick answer. Each issuer can block an address onchain. Blocked USDC addresses cannot send or receive. Blocked USDT addresses on Ethereum cannot send, and Tether can destroy the balance. A company's wallet can be frozen the same way.

Watch: USDC Blacklist and USDT Freeze Functions Explained 1:41

Video transcript

Circle and Tether can each freeze an address onchain, including the wallet holding your customers' funds.

Tether says it froze more than 1.5 billion dollars of USDT within 30 minutes of the Binance hack.

Both tokens keep a blocklist that every transfer checks. Blocked USDT on Ethereum can still receive but not send, and Tether can destroy the balance. Blocked USDC can do neither.

USDT's owner was a three of six multisig, and USDC's blacklister an address with no contract code. Circle's policy cites legal orders, sanctions and network threats. Tether's terms also allow freezes it judges prudent.

Both contracts flag whole addresses, not individual tokens. So if your omnibus wallet is blacklisted, every customer balance of that token there freezes together.

Withdrawals fail on both. But USDT keeps accepting deposits into a frozen wallet, and mistaken sends do not bounce. USDC rejects both, so USDT is harder to operate.

Blocking an address on one chain does not block it on another. On Solana, freezes hit token accounts, and bridged USDC can have a third-party blacklister.

Screen addresses before you send, and screen what arrives. Split wallets, alert on freeze events, write the issuer playbook, and rehearse it on a fork.

Guardian's fintech pentests attack the flows that approve withdrawals, function by function. Read the full article, or talk to Guardian at guardian.security.

Tether says it froze more than $1.5 billion of USDT within 30 minutes of the October 29, 2026 Binance hack.

The same functions can freeze a fintech's own wallet. This guide reads them in the contracts, then covers what they mean for omnibus wallets.

For the regulatory side, see stablecoin freeze requirements under MAS, HKMA and the GENIUS Act.

How the Freeze Functions Work

Both tokens keep a list of blocked addresses inside the token contract. Every transfer checks it.

	USDT on Ethereum	USDC (FiatToken v2.2)
Freeze	`addBlackList`	`blacklist`
Unfreeze	`removeBlackList`	`unBlacklist`
Caller	Owner	Blacklister role
Blocked address can send	No	No
Blocked address can receive	Yes	No
Remove the frozen balance	`destroyBlackFunds`	None in v2.2
Event	`AddedBlackList`	`Blacklisted`

USDT on Ethereum

Tether's TetherToken contract is verified on Etherscan. addBlackList and removeBlackList set a flag per address, and only the owner can call them.

transfer checks require(!isBlackListed[msg.sender]). transferFrom checks the _from address. Neither checks the recipient.

destroyBlackFunds works only on a blacklisted address. It zeroes the balance and cuts total supply by the same amount.

Tether says it has returned frozen funds to owners and law enforcement through reissuance. The owner can also pause all transfers.

USDC (FiatToken)

Circle publishes the code in its stablecoin-evm repository. blacklist and unBlacklist carry the onlyBlacklister modifier.

Circle's design document says a blacklisted address "will be unable to call transfer or transferFrom, and will be unable to receive tokens." Mints to it fail too.

From v2.2, it can call approve, "but they are still blocked from transferring the assets in any way."

No FiatToken function burns another holder's balance; minters burn only their own.

USDC sits behind an upgradeable proxy, though, so its admin role can replace that code.

A separate pauser role can stop all transfers.

Who Can Trigger Them

We read both tokens on Ethereum at block 26,357,581 on November 6, 2026.

USDT: the owner was a MultiSigWallet contract needing 3 of its 6 signers.
USDC: the blacklister was an address with no contract code. The owner, a separate address, can replace it.

Circle's design document says: "Circle will control the address of all roles." The chain cannot show what signing control sits behind an address with no code.

The published policies

Circle's Stablecoin Access Denial Policy says Circle "will not deny access to individual addresses" except in three cases.

A threat to the security or integrity of the network, such as a compromised minter key, in Circle's "sole discretion."
A law, regulation or legal order from a recognized US or French authority or court, or another authority with jurisdiction.
Urgent law enforcement requests pending a court order, sanctions or national security requests, and orders pending a treaty process.

Circle may reverse a block on formal confirmation that the order no longer applies, or that the security incident has passed.

Tether's Terms of Service (updated February 26, 2026) let it freeze tokens when required by law, when it "determines it is prudent to do so," or on a breach.

Tether also says its wallet freezing policy is "aligned with OFAC's Specially Designated Nationals (SDN) List."

How US law treats these powers is in the GENIUS freeze mandate and the SEC's central party test.

Impact on Omnibus Wallets

A freeze hits an address, not a customer. Circle's policy is explicit: "It is not possible to deny access to individual Circle Stablecoin tokens."

So if an omnibus wallet is blacklisted, every customer balance of that token at that address is frozen together.

The two tokens then behave differently:

What happens	USDT on Ethereum	USDC
Customer withdrawals from the frozen wallet	Fail	Fail
New deposits into it	Succeed, then stuck	Rejected
You send to a blacklisted address	Succeeds; funds stuck there	Rejected
Issuer removes the balance	Possible	Not in current code

The USDT case is the harder one to operate. Deposits keep landing in a frozen wallet, and a mistaken send does not bounce.

Pools and vaults have the same shape. Blacklist a pool's address and every depositor's share of that token is frozen.

Cross-Chain Differences

Every deployment is a separate contract with its own list. Blocking an address on one chain does not block it on another.

Deployment	Freeze	What it blocks
USDT, Ethereum	`addBlackList`	Sending
USDT0, Arbitrum	`addToBlockedList`	Sending, and `transferFrom` called by a blocked address
USDC, EVM chains	`blacklist`	Sending and receiving
USDT and USDC, Solana	`FreezeAccount`	Any instruction on the frozen token account

On Arbitrum, USDT0's verified source exempts calls by the owner from the sender check. destroyBlockedFunds burns a blocked balance.

On Solana, the SPL Token program freezes a token account, not a wallet. The docs say instructions that include a frozen account "will fail until the Account is thawed."

There, USDT's freeze authority was an SPL multisig needing 2 of 3 signers, and USDC's needed 2 of 4.

Bridged copies are different again. Under Circle's Bridged USDC Standard, the third-party team holds the blacklister role until both sides agree to hand it to Circle. See USDC.e vs USDC.

Reducing Exposure

Screen before you send. Call isBlackListed on USDT or isBlacklisted on USDC for the destination.
Screen what arrives. Run deposit sources through your analytics provider before crediting.
Split wallets. Separate deposit, hot, cold and settlement addresses, and cap the balance in each.
Watch your addresses. Alert on AddedBlackList, DestroyedBlackFunds, Blacklisted and pause events.
Map every chain. List each deployment and bridged version you support, and who holds its freeze role.
Write the issuer playbook. Who contacts Tether and Circle, with what evidence, and what lifts a block.
Set customer terms. Say what happens to balances if an issuer freezes a shared address.
Rehearse it. On a fork, freeze a test address and run your deposit and withdrawal flows.

How Guardian Helps

Guardian's fintech pentests attack the flows that authenticate users, authorize actions and approve withdrawals, function by function.

Managed Security keeps those controls in place as you grow.

For issuers, the work reaches the token itself. For USAT, Tether's US-regulated stablecoin, Guardian ran a 62-test fork suite over the blocklist, permit, mint and redeem paths.

Frequently Asked Questions

Can Circle freeze USDC in my wallet?

Yes. Circle's blacklister role can block any address from sending or receiving USDC. Circle's policy limits this to legal orders, some urgent law enforcement, sanctions or national security requests, and threats to the network's security.

Can Tether freeze USDT?

Yes. On Ethereum, USDT's owner can blacklist an address so it cannot send, then destroy its balance. Tether's terms allow freezes when required by law, on a breach, or when Tether judges it prudent.

Can a blacklisted address still receive USDT?

On Ethereum, yes. TetherToken checks only the sender, so transfers into a blacklisted address succeed and the funds are then stuck. USDC rejects transfers to a blacklisted address.

What happens to customers if an exchange's wallet is frozen?

Every customer balance of that token held at the address is frozen together. Circle's policy says it cannot block individual tokens, only addresses. Withdrawals from that address stop until the issuer lifts the block.

Sources

Test the flows a freeze would hit

Guardian pentests the value-moving flows behind your platform, from authorization to withdrawal approval, function by function.

Talk to Guardian Explore fintech security