The U.S. IRS has published a practice (process) unit on the Allowance of Deductions and Credits on 1120-F Delinquent Returns. The process overview includes the following: A Form 1120-F filer is entitled to reduce its gross income by deductions and credits (other than the credit provided under IRC 33 for tax withheld at source and the deduction for charitable contributions allowed under IRC 170, whether or not connected to effectively connected income (ECI)) only if its return is timely filed. For this purpose, a foreign corporation's return is timely if it is filed within18 months after the return's due date...