If you have been charged a penalty but believe you have reasonable cause (e.g. casualty, disaster) for not complying with the tax laws, you may request a waiver of penalty (abatement of penalty). Reasonable cause may exist when you show that you used ordinary business care and prudence and were still unable to meet the requirements for filing your return and paying the amount owed on time. To request a waiver of penalty due to reasonable cause, write to us at the address on the notice you received and provide a detailed explanation of your current circumstances and any documentation that supports your position. We will review your request and respond in writing. If you have any questions, call us at the telephone number written on the notice. For more information, see the Reasonable Cause Regulations and Publication 103 – Penalties and Interest for Illinois Taxes.