Kane County supervisor of assessments explains rise in 'certificates of error,' urges residents to check property records

Supervisor of Assessments Mark Armstrong told the Kane County Public Service Committee on Jan. 23 that the county’s increase in “certificates of error” largely reflects corrections for missing exemptions and legacy data issues, and he urged residents to review their property record cards online.

Armstrong said the Board of Review is scheduled to certify the assessment roll on Jan. 30, which will give the county clerk and treasurer time for customary cross-checks before tax bills are mailed. “Check your property record card. It’s the easiest thing to fix,” Armstrong told the committee, describing the property record card as a digital record maintained by township assessors.

Armstrong explained that a certificate of error is the statutory term for a correction to a tax bill; the most common cause is a missing homestead exemption. He said the county mails applications to seniors who qualify for the senior freeze but typically receives only about 6,000–7,000 returns from roughly 30,000 mailings. That mismatch, Armstrong said, is a frequent source of retroactive corrections.

He described other causes, including historical field notes and older property measurements that, when compared with higher-resolution modern aerial photography, sometimes reveal discrepancies. Armstrong said Kane County has about 200,000 parcels and that township assessors maintain the detailed records used to generate assessments.

Armstrong and committee members discussed outreach possibilities. Armstrong said the assessor’s office and township assessors already provide a quick guide and that residents can view records at assessments.kanecountyl.gov and contact their township assessor for details.

Why it matters: Certificates of error can generate refunds or adjustments to tax bills and thus affect county revenue timing and taxpayers’ bills. Armstrong framed the issue as a mix of statutory requirements, taxpayer response rates, and decisions about cost-effective outreach.

Details: Armstrong said the assessor’s office avoids spending more to capture small gains, citing the trade-off between outreach cost and potential refund amounts. He also recounted a recent example in which a building permit for a patio existed but the patio was never built, which the assessor reconciled after reviewing aerial imagery.

What’s next: Armstrong encouraged residents to review their digital property record cards and said the assessor’s office will continue to explore low-cost outreach methods, including email lists and potentially QR codes, while coordinating with township assessors.