The property tax bill you can fight is not the one in your hand now

The envelope that shows up with a number large enough to make you sit down is, in most of the country, the one document in the property tax process you can do nothing about.

There are two mailings, and homeowners tend to notice only the second. The first is the assessment notice, the county's statement of what it believes your property is worth. The second is the tax bill, which takes that value, applies the local rates, and tells you what you owe. The appeal window is attached to the first mailing.

According to the Illinois Department of Revenue, once the tax bill has arrived it is generally too late to challenge that year's assessment. Illinois is typical rather than unusual here. Deadlines vary by state, but they commonly run about 30 to 45 days from the date the notice is mailed, and some are shorter.

That timing explains why so few owners ever appeal. The notice arrives months ahead of the bill, carries no amount due, and reads like a form letter, so it goes in a drawer. The bill arrives later and produces the reaction. By then the deadline has passed and the value is locked in for the year — and in places that reassess only every few years, for longer than that.

There is one useful thing to do while holding a bill you cannot appeal. Call the county assessor's office or check its website and find out what month assessment notices go out. Put that month on next year's calendar, and open the envelope when it comes.

The mailing that matters is the one that never tells you what you owe.