Software Filing Error Inflated Valencia County Property Tax Bills, Officials Say

Valencia County Assessor Celia Dittmaier said the countywide taxable value that should have been reported as $200 million was submitted as $2 billion, a filing error she and county officials say nearly doubled the county operational mill rate and produced inflated bills for some homeowners. Dittmaier said the incorrect submission drove the operational mill rate from about 6.82 mills to about 11.85 mills and helped trigger roughly a 22% increase on affected property tax bills.

Some homeowners reported the error as an immediate out-of-pocket problem, with multiple residents saying they saw about an extra $600 on a single bill and others describing themselves as shocked when they checked their statements. County and state reporting indicated residents have expressed worry about the unexpected increases and potential financial strain.

County officials say the Assessor’s Office re-submitted corrected property values to the state property tax division Thursday morning and is working with software vendors and the Local Government Division of the Department of Finance and Administration to identify the root cause, recalculate mill rates, and issue corrected bills. Treasurer Ron Saiz said the 2025 property tax mill rates were determined using an incorrect net taxable value and that the county plans to send updated Valencia County property tax bills once the corrected numbers are available.

Officials and the state offered a deadline for completing the technical fix: the state property tax division told county staff the correction should be implemented by the December 10 deadline. County leaders also announced operational steps intended to reduce immediate harm: penalties will be waived for property taxes due on Dec. 10, and the Treasurer’s Office has posted additional hours to assist taxpayers.

Status reports on whether corrected bills have already been mailed differ in county briefings. County statements to local media have described the problem as everything from a simple typo to a software issue that prevented corrected bills from being sent; at the same time the county has said all property taxes have been corrected and that the Treasurer’s Office will be open Saturday from 10 a.m. to 3 p.m. for residents who need help. The Treasurer’s Office asks anyone with questions to call 505-866-2090, and the county website offers a callback request option.

County leaders approved an investigation into the error in November, and county officials say that probe will explore how the $200-million figure became a $2-billion submission, whether the filing mistake was human, software, or process related, and what systemic fixes are required. The county says it will send corrected bills and notify taxpayers once the state completes processing of the revised net taxable values.