Tostrud & Temp SC, a certified public accounting firm in La Crosse, Wisconsin, has sent a notice about a recent data security incident that may have involved personal information. This page summarizes what its notice and the Massachusetts breach report say so far.
Tostrud & Temp SC’s Data Breach Investigation
Tostrud & Temp SC is a full-service CPA firm in La Crosse, Wisconsin, that serves businesses, individuals, governments and non-profit organizations. It has told people that a recent data security incident may have involved their personal information. Its notice letter is dated October 21, 2026, and a sample was filed with the Massachusetts Office of Consumer Affairs and Business Regulation and posted on the state’s website. The state’s 2026 breach report lists the matter as involving 2 Massachusetts residents.
The letter says very little about the incident itself. It does not describe what happened, when the firm found out, when any unauthorized activity began or ended, or whether the cause was an outside attack, a mistake or the loss of a device. It states only that the incident may have involved the recipient’s personal information, and that the firm takes the privacy and security of the information in its possession very seriously. The letter is a sample with its addressee and enrollment details left as placeholders.
The Massachusetts breach report adds some detail on the type of data. It classifies the firm as a financial services company and flags three categories as breached: Social Security numbers, financial account information and driver’s license numbers. It does not flag medical records or credit and debit card numbers. Those flags come from the state’s summary and not from the text of the letter, so each recipient should check their own notice for what applies to them.
No total number of affected people has been published. The figure of 2 covers only Massachusetts residents, and a firm of this kind, which prepares tax returns for clients in many states, may have sent notices to people elsewhere. The firm has not said how many clients, employees or others were notified, or whether its own systems or those of a vendor were involved.
The letter states that the firm has no evidence of any misuse or attempted misuse of potentially impacted information. To help relieve concerns, it is offering credit monitoring and identity protection through Experian IdentityWorks at no cost. The services include 24 months of credit monitoring, and the letter says people must enroll by December 31, 2026, using an enrollment code in the mailed copy. A credit card is not required to enroll.
The offer also includes Experian identity restoration. The letter says an Experian agent is available to investigate and resolve each incident of fraud that occurred from the date of the incident, including help contacting creditors, and that identity restoration is available for 24 months from the date of the letter. People who believe their information was used fraudulently are directed to contact Experian, and an alternative to online enrollment is available by phone.
Accounting firms hold some of the most complete financial profiles of any business: tax returns, Social Security numbers, bank account details, payroll records and identification documents for their clients. That concentration makes them attractive targets, and an incident at one firm can touch many people who never dealt with the firm directly, such as the employees of a business client or beneficiaries listed on a return. A Social Security number combined with a driver’s license number and account information can support fraudulent accounts, false tax filings and impersonation of the victim.
Because tax data is involved, people who receive a notice from a CPA firm may also want to consider an Identity Protection PIN from the IRS in addition to the credit freeze and fraud alert options below. If you received a letter from Tostrud & Temp SC, keep it and the envelope. Attorneys are looking into whether the firm took reasonable steps to protect client information and whether its notice to affected people met the standards that apply.
When Did This Breach Occur?
The notice does not say when the incident happened or when Tostrud & Temp SC discovered it. The letter is dated October 21, 2026, which is the date the firm began communicating with affected individuals. The firm has not published a timeline of when any unauthorized access began, was detected or ended, so the timing of the underlying event should be treated as unknown for now.
What Information Was Breached?
The notice says only that personal information may have been involved. The Massachusetts breach report flags Social Security numbers, financial account information and driver’s license numbers as breached, and does not flag medical records or credit and debit card numbers. The firm says it has no evidence of misuse or attempted misuse. Not every person will have had every type of data involved, so your own letter is the best guide to what applies to you.
What You Can Do
If you received a notice related to Tostrud & Temp SC or believe you may be affected, consider these steps:
- Read the notice carefully and keep it, along with any enrollment details for protection services it offers.
- Enroll in the 24 months of Experian IdentityWorks offered in the letter before the December 31, 2026 deadline, using the enrollment code in your copy.
- Place a free fraud alert or a credit freeze with Equifax, Experian and TransUnion, and get your reports free at annualcreditreport.com.
- Review bank, card and insurance statements for anything you do not recognize.
- Be skeptical of unexpected calls, texts or emails that mention the incident, and report suspected identity theft to the Federal Trade Commission at identitytheft.gov.
File a Data Breach Lawsuit Against Tostrud & Temp SC
If you received a notice from Tostrud & Temp SC, or you believe your information was involved, you may have legal options for holding the firm accountable for how it protected your Social Security number, financial account details and other sensitive information.
Contact us at Class Action U, where we’ll connect you with a lawyer skilled in class action lawsuits. If you’ve been contacted about this breach, received notice, or discovered you were impacted, fill out our quick, easy, and secure form to sign up. There is no cost to reach out to our legal partner and no obligation after speaking with someone from our team.
