Tether disclosed on September 28 that it assisted U.S. authorities in freezing approximately $550 million in USDT during 2026 across wallets linked to Iran's central bank and sanctions networks.

The tally includes more than $344 million frozen across two addresses in April and more than $130 million across four wallets in July. Tether provided no per-action reconciliation.

What does the Senate report say?

A minority staff report from the Senate Permanent Subcommittee on Investigations, prepared with Sen. Richard Blumenthal, found that USDT dominated activity in 84% of 846 Iran- and proxy-linked wallets it studied.

That share measures the stablecoin's prevalence within a sanctions-defined wallet set, not its slice of all Iranian payments. The study drew on addresses flagged by OFAC and Israel's National Bureau for Counter Terror Financing between June 2021 and August 2026.

The report alleged that Tether sometimes took weeks to blacklist illicit wallets or did not do so. It identified $34.6 million that continued flowing through sanctioned wallets after designation.

How do on-chain records corroborate the freezes?

USDT contract event logs on Tronscan show the two April addresses blacklisted on April 23. OFAC listed them under the Central Bank of Iran's entry a day later.

The four July addresses were blacklisted on July 14. OFAC's update landed the same day, appending all six addresses to the same sanctions designation.

Chainalysis reported in July that central-bank wallet freezes totaled almost $475 million, roughly $75 million below Tether's year-to-date figure.

What is Tether's response?

Tether's statement did not reference the Senate report. It stressed operational cooperation and said its work globally had helped freeze more than $4.9 billion in assets.

"Tether can act when credible information is provided by law enforcement," CEO Paolo Ardoino said in the statement.

The Senate report noted that Tether acknowledged a June 4 request for information about Iranian shadow banking but had not responded by the report's publication.

What changes for stablecoin enforcement?

The disclosure lands as Treasury expands its crypto-focused sanctions architecture. OFAC has integrated Tron and Ethereum address data directly into the SDN list since 2024.

Stablecoin issuers now sit as de facto enforcement intermediaries. Blacklists execute at the smart-contract level, bypassing correspondent banks entirely.

The Senate minority staff is likely to press Tether on the lag between wallet identification and blacklisting, with focus on compliance staffing at the issuer level.