Unfortunately, yes. Even if it's just a partial tax year, you are responsible for filing tax forms for each year that your business is in existence -- regardless of whether it is generating revenue. Rather than form an entity so close to the end of the year, entrepreneurs might want to wait until January, and start the tax year afresh, unless they have a compelling reason to do otherwise . . . which they should discuss with their attorney and accountant.
Creating a MAP will take no more than an hour of your time every month and will keep the lines of communication open, ensuring relationships with investors remain strong, and ultimately helping early-stage startups succeed.