2018 Fall NewsletterTax and Financial Planning Calendar for October 2018 October 1, 2018 cutlerschwartzschwartz Month Income Taxes Saving and Investing OCTOBER Tax returns on extension due 10/15/18 Find out how to complete your W-4 form correctly using the IRS’ On-line Withholding Calculator Taxpayers on extension must fund retirement accounts by October 15th 5500s for retirement plans that were put on extension by 07/31/18 need to be filed by 10/15/18.