The Illinois Department of Revenue (IDOR) sends letters and notices to request additional information and support for information you report on your tax return. For a property damage claim you should submit two written itemized estimates attached on company letterhead or an itemized paid invoice with proof of payment.What to include in the Chicago demand letter? If you need help filling it out, your caseworker will help you. You do not need to include court costs. The letter must be in its original form, signed and dated within 45 days prior to being mailed to the Illinois Secretary of State's office. This Easy Form helps you make a letter asking your landlord for your security deposit back. This Easy Form does not send your letter. The official website of the City of Chicago Department of Finance, otherwise know as the Comptroller's Office. The IRS Trust Fund Recovery Penalty (TFRP) can put individuals on the hook when a business fails to pay certain taxes on time.