HackingProfessional ServicesProfessional ServicesStolen CredentialsCapture Stored DataData ExfiltratedRansom DemandedTargetedIdentity (basic)Government IDFinancial accountEmploymentMediumContained

Guthmann Tax Services

bd_7abe27a46b47bfef · schema v1 · pii pii-v1

Severity

Medium

Discovered

Jun 25, 2025

Filed

Oct 7, 2025

To disclose

15 weeks

Affected

1state residents only

Linked

3 filings

Confidence

64%

Full breach record for Guthmann Tax Services →

Guthmann Tax Services, Inc. notified Montana residents of a data breach where unauthorized parties accessed client systems between June 16-18, 2025, to file fraudulent tax returns. The incident involved access to PII, SSNs, and financial data. The company engaged forensic investigators, notified the IRS, FBI, and Secret Service, and is offering 12 months of identity monitoring services.

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Incident timeline

undetected · 9 days

discovery → filing · 15 weeks / 104 days

Jun 16, 2025

Begins

Jun 25, 2025

Discovered

Oct 7, 2025

Filed

vs. sector median

4 wks faster

This filing is one of 3 about the same incident.View merged incident

Linked disclosures

Why this link?

Regulatory filings (2) · sorted by filing gap

Maine State AGbd_4fe407fdd520662d2025-10-07Candidate
Indiana State AGbd_ac18a4d13f489b542025-10-07Verified

Name: Guthmann Tax Services
norm: guthmann tax

Name: Guthmann Tax Services
norm: guthmann tax
Industry: Professional Servicesllm

Discovered: Jun 25, 2025
Breach occurred: Jun 16, 2025 – Jun 18, 2025
Undetected for: 9 daysoccurrence → discovery
Materiality determined: —
Notification sent: —
Affected individuals: 1state-resident count only
Data types: Identity (basic)Government IDFinancial accountEmployment
Attack vector: Unauthorized Access
MITRE ATT&CK: T1078 Valid AccountsT1041 Exfiltration Over C2 Channel
Threat actor: ExternalFinancial
Regulator citations: Notified and began working with the Internal Revenue Service (IRS)Notified appropriate state tax agenciesReported this matter to the FBI and Secret Service
Initial access: valid_credentials

During the incident: Terminated the threat actor’s access
Engaged a forensic specialist to investigate
Notified and began working with the Internal Revenue Service (IRS) and the appropriate state tax agencies
Changed our office’s EFIN with the IRS
Implemented additional security measures to further protect our network
Installed advanced security software
Isolated affected systems
Changed login credentials across our environment
Engaged cybersecurity experts to perform a comprehensive forensic investigation
Reported this matter to the FBI and Secret Service
Requested additional records from our tax software provider
Changes made: Installing advanced security software
Isolating affected systems
Changing login credentials across our environment
Providing access to Identity Monitoring services at no charge for 12 months
Providing proactive fraud assistance
Source: Quoted from the filing itself, not independently verified.

Time to disclose: 15 weeks(104 days from discovery to filing)
Compliance flags: — (clock not assessable for this source)

Status: No extraction artifact recorded for this disclosure.

Filing propagation · 3 filings · 3 states

View merged incident ↗

Maine State AGOct 7 · first

Indiana State AGOct 7 · first

Montana State AGOct 7 · first · this page

Evidence ladder

Leak-site claim

Attacker assertion only. Establishes: claim date, group, alleged victim.

Press / market report

Unlocks: incident narrative, operational impact. Still no compliance clock.

State AG / regulator filingThis record

Unlocks: discovery date, data types, affected count, compliance clock.

SEC 8-K / victim statement

Unlocks: materiality, stated response, full audit trail. Ceiling removed.

Source URL: https://dojmt.gov/wp-content/uploads/2026/05/Consumer-notification-letter-12.pdf
DisclosureLens links to the originating regulator URL — full filing bodies are not redistributed from public surfaces (§4.5).
Filed at: Oct 7, 2025
Raw hash: 958c847260959e2fe516ac078d80292dfeffbe32f76caaf3e2914c6727d0636d

Linked disclosures

Regulatory filings (2) · sorted by filing gap

Reporting entityGuthmann Tax Services

Victim entityGuthmann Tax Services

Incidentdiscovered Jun 25, 2025

Stated responseTerminated the threat actor’s access

Complianceclock not assessable

Extraction provenanceno artifact recorded

Source provenancedojmt.gov