5 Common Tax Mistakes Startups Make From Paperistic (@paperistics) It's tax time. Filing taxes can be a real learning curve for many young founders and small-business owners. Unknowingly, they might be leaving hundreds, even thousands of dollars off the table. Often times, entrepreneurs are simply not aware of deductions. Another big mistake new entrepreneurs make is not keeping records of expenses. Receipts are easy to lose and if you can't prove it, you can't deduct it. To save headaches and money, go through these 5 common mistakes and tips on how to avoid them.