Hallisey & D'Agostino Data Breach Affects 16,683 People

Hallisey & D'Agostino, LLP, a full-service accounting firm based in Wethersfield, Connecticut, experienced a data breach that affected 16,683 individuals in the United States.

The breach was reported to the Maine Attorney General, with 74 Maine residents identified as affected. According to the filing, the breach was discovered on March 19, 2026. The company plans to begin notifying affected consumers in writing on April 17, 2026.

On Oct. 21, 2025, Hallisey & D'Agostino identified unusual activity in its computer network, according to the company's notification to consumers. The firm took immediate steps to secure its network and launched an investigation with the support of external cybersecurity experts.

The investigation determined that an unknown actor gained unauthorized access to the firm's network over a period of roughly 24 days, between Sept. 28, 2025, and Oct. 22, 2025. During that time, the actor potentially acquired certain files from the firm's systems. Some of those files may have contained personal information belonging to individuals connected to the firm.

In addition to the Maine residents identified in the state attorney general filing, the company's consumer notice indicated that 162 Rhode Island residents were also affected by the breach.

Hallisey & D'Agostino's response

The firm is offering affected individuals complimentary identity theft protection services through IDX, a data breach and recovery services provider. The services include credit and CyberScan monitoring, a $1,000,000 insurance reimbursement policy and fully managed identity theft recovery services.

Affected individuals can enroll in the identity protection services by visiting the IDX enrollment page or by calling 1-888-201-9274. Each affected individual will receive a unique enrollment code in their written notification letter, which is required to complete the enrollment process. The deadline to enroll in these complimentary services is July 17, 2026.

Hallisey & D'Agostino has also set up a dedicated toll-free call center to assist individuals who have questions about the incident. The call center can be reached at 1-888-201-9274 and is available from 9 a.m. to 9 p.m. Eastern Time, Monday through Friday, excluding major U.S. holidays.