National Tax Service
Outcome
Keisy Altagracia Sosa, operator of National Tax Service in Las Vegas since at least 2007, pleaded guilty March 12, 2025 to preparing false returns for clients from 2016–2021 that claimed fictitious dependents, fabricated Schedule A itemized expenses, and false Schedule C business expenses — causing at least $550,000 in IRS losses — continuing the fraud even after receiving multiple IRS warning letters about inaccurate returns.
Details
National Tax Service / Keisy Altagracia Sosa — False Returns Despite IRS Warnings, Las Vegas (2025)
Outcome: Keisy Altagracia Sosa, who had operated National Tax Service in Las Vegas, Nevada since at least 2007, pleaded guilty March 12, 2025 to preparing false federal tax returns for clients from 2016 through 2021 — fabricating dependent claims, Schedule A itemized deductions, and Schedule C business expenses — causing at least $550,000 in IRS tax losses, despite receiving multiple IRS warning letters over the period informing her that her returns appeared inaccurate.
National Tax Service operated as a community tax preparation business in Las Vegas, Nevada, with Keisy Altagracia Sosa as its longtime operator. From 2016 through 2021, Sosa prepared and filed false federal tax returns for clients that incorporated multiple categories of fraud: fictitious dependents that did not exist or were not qualifying individuals, false Schedule A itemized deductions including fabricated sales taxes paid and invented unreimbursed employee expenses, and false Schedule C business expenses purportedly connected to client businesses that had no legitimate operations or expenses.
The case is particularly notable for the documented IRS enforcement response that Sosa ignored over multiple years. During the 2016–2021 period, the IRS sent Sosa multiple letters — not once but repeatedly — notifying her that the returns she filed appeared inaccurate, informing her that she might not be meeting her paid preparer due diligence requirements, reminding her of those obligations, and directing her to educational resources about return preparer compliance. Sosa continued preparing false returns despite each of these notices, demonstrating willful disregard of repeated federal regulatory warnings.
Primary Source: IRS Criminal Investigation — Las Vegas Return Preparer Pleads Guilty to Filing False Tax Returns
How Crucible Prevents This
Crucible's instinct-observer hook would detect the pattern of false dependent, Schedule A, and Schedule C entries appearing simultaneously across a long-term preparer's client portfolio. The pre-tool-check hook would surface the IRS warning letters about return inaccuracies at every session start — the regulatory notices that Sosa ignored for multiple years. The quality-gate would block any return containing Schedule C expenses without documented business verification.
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