Do you need a lawyer to appeal your property taxes?
For a house, usually not. For a corporate-owned property at PTAB, usually yes.
Illinois lets a property owner represent themselves at the Board of Review. Most residential appeals are self-filed, and boards are used to it.
When you do not need one
A single-family home, a uniformity or factual-error argument, evidence from public records. The procedure is a form and a hearing, and nothing about it requires legal training.
When you probably do
Property owned by a corporation or LLC — at the Property Tax Appeal Board, entities generally must appear through a licensed attorney, because an entity cannot represent itself. Commercial and industrial property, where income-approach evidence and an appraisal are usually needed. Cases going to circuit court.
The middle option
Contingency-fee tax appeal firms take a share of the first year's saving. For a large or complicated property that can be good value. For a modest residential appeal where the evidence is a handful of public records, you are paying a share of the saving for work you could do in an evening.
How to decide
Estimate the annual saving. If it is a few hundred dollars and the argument is uniformity from public records, do it yourself. If it is thousands, the property is commercial, or the case rests on a valuation opinion, get professional help.