Automatic Illinois six-month extension​​ We automatically grant you a six-month extension of time to file your tax return. We grant an automatic six-month extension of time to file your return.Submit proof of IRS approval when available. In the case of automatic filing extensions, proof of timely mailing of Form 4768 to the IRS will be accepted. Under these acts, a product's regulatory review period forms the basis for determining the amount of extension an applicant may receive. Ensure effective and efficient program administration and long-term compliance for the largest portfolio of affordable multifamily rental housing in Illinois. Illinois offers a 6-month extension, which moves the filing deadline from April 15 to October 15 (for calendar year filers). (Section 21B-45(e)(9) of the Code). The real industry situation and could yield a highly credible and quality result. 4.2. Current practice in assessing EoT claims.