I just recently did this for my investment property. The township is very helpful and said as soon as you can, get the forms to fill out and any other information they need. The change will not occur until the 2010 tax bll because it is so late in the year.
Yes, you can appeal your property taxes in McHenry County. Find out what township the property is located in and give the township office a call. They should give you direction is what is required and when. As an appraiser and realtor, the township staffs are very friendly and will certainly answer your questions. Good luck in your quest and feel free to call me anytime if I can be of further service. Blessings, Mark Tracy \ Keller Williams Success Realty & Market Data Research, Inc (my appraisal company).