O’Connor is the largest property tax consulting firm in the U.S. We have developed the largest database of residential and commercial properties with complete valuation data. This allows us to compare assessed valuations and projects if your property is over or undervalued by your local assessor. Giving you property tax relief. If you need help appealing your property taxes, we have a team of professional, licensed tax consultants and administrative support team that works with property owners by reducing property tax assessments, filing personal property renditions, reviewing tax statements, protesting over-assessed property values, and attending informal tax hearings and appraisal review board meetings.