Tax-MT Data Breach Exposes Client Social Security Numbers

Tax-MT PLLC, a boutique tax advisory and preparation firm based in Billings, Montana, disclosed a data breach that may have exposed clients' Social Security numbers.

The incident was disclosed to the Massachusetts Office of Consumer Affairs and Business Regulation on Oct. 27, 2026. Tax-MT began notifying consumers on Oct. 20, 2026, through written notice.

On July 21, 2026, a ransomware group known as PLAY posted a claim on the Tor network stating it had obtained data belonging to Tax-MT and threatened to publish the stolen data within five days. The compromised data allegedly included private and personal confidential data, client documents, budget, payroll, IDs, taxes and finance information.

The type of personal information confirmed by official disclosures as potentially exposed included Social Security numbers.

Tax-MT's response to the breach

The company is offering 24 months of complimentary credit monitoring and identity protection services through Experian. The deadline to enroll in these services is Jan. 29, 2027.

Affected individuals can enroll by calling 1-833-918-5936 or by visiting the Experian IdentityWorks enrollment page. An enrollment code was included in each individual's notification letter.

A dedicated call center is available at 1-833-918-5936 between 7 a.m. and 7 p.m. Mountain Time, Monday through Friday, excluding major U.S. holidays.