What is “black U” or “dirty U”?

Not all USDT in circulation is equal. Some USDT has passed through illegal fund chains such as online gambling, fraud and money laundering, and has been flagged by exchanges or the issuer as risky — known in Chinese crypto circles as “black U” (黑U) or “dirty U” (脏U). Tether has disclosed that it once froze USDT worth USD 2.9 billion in a single action.

The consequences of receiving dirty USDT

Once USDT you receive is deemed to be of unknown origin or linked to a case, the exchange or Tether can freeze it directly, and ordinary users have almost no room to appeal — the money is essentially gone.

Three practical ways to reduce risk

Receive at an exchange wallet address

Receive funds at your deposit address on a major exchange, or a reasonably sized mid-tier exchange, rather than a personal wallet address. Exchanges screen the on-chain source of USDT on deposit, and funds from suspicious sources such as online gambling or dark pools are intercepted — the exchange acts as your first line of defence.

Check the counterparty’s address

Where possible, ask the counterparty for the wallet address they will send from, and check on a blockchain explorer whether it has links to known risky addresses.

Beware of prices well off the market

If the counterparty’s price is clearly below the normal market rate, be on guard — an unusually low price often signals a seller eager to offload suspicious funds.

What if it’s already frozen?

If USDT you received is frozen by an exchange, immediately preserve complete transaction and chat records, consult a lawyer promptly to assess the source of funds and your own legal position, and if necessary cooperate with the police investigation to show you did not know — rather than waiting passively or trying to move the funds.

How Wang Xin’s team can help

  • Releasing frozen crypto and bank accounts
  • Defense in crypto-related criminal cases
  • Compliance review of funds involved in cases

If your USDT or bank account has been frozen, contact Wang Xin: phone +86 186-0113-9509, WeChat wang223040.

Quick answers

What is “dirty” or “black” USDT?
USDT that previously passed through illegal fund flows such as online gambling, fraud or money laundering, and has been flagged as risky by exchanges or the issuer. It can be frozen at any time.
How can I reduce the risk of receiving tainted USDT?
Receive at a deposit address on a major or reputable exchange, which screens on-chain sources; check the sender’s address on a blockchain explorer beforehand; and be wary of prices well below market.
What should I do if my USDT is frozen?
Preserve all transaction and chat records, consult a lawyer about the source of funds and your legal position, and if necessary cooperate with police to show you did not know — don’t wait passively or try to move funds.

This is an English edition of Wang Xin’s original Chinese article, 收USDT收到黑U/脏U怎么办？交易所地址收款能帮你避坑. It explains the law of the People’s Republic of China in general terms and is not legal advice for any particular case; outcomes depend on the specific facts and on how local authorities apply the rules.