I have a small business where I sell antiques on the side. I do this with 2 other family members. Can I claim what I pay the three of us as a business expense?

If three people participate in the business together, you need to have a serious discussion about income taxes and business structure.  This all assumes you are not a corporation or multi-member LLC, if you are, then ignore everything else and write back, you may need a CPA.

If you are an unstructured business, you basically have 3 options.

1. Single owner with employees.  There is one single owner (maybe you).  All income and expenses are reported on one Schedule C.  Anyone who helps with the business is an employee.  You pay wages, deduct taxes, and issue a W-2 at the end of the year.

2. Single owner with subcontractors.  There is one single owner (maybe you).  All income and expenses are reported on one Schedule C.  Other people who materially participate in the business is treated as a subcontractor or independent contractor.  They receive money, and they are issued a 1099-NEC.  They report themselves as self-employed contractors and file schedule C on their tax returns, but they don't have business expenses of their own, just the money they are paid for helping out.

3. Three owners (partnership).  The business files a form 1065 Partnership Tax Return to report all the income and expenses of the partnership.  Pass-through income and expenses are reported on K-1 statements issued to each partner that come out of preparing the 1065.  Each partner lists the K-1 on their tax return instead of including a schedule C.

Note that the partnership 1065 is due March 15, not April 15 (unless you get an extension) and the late fees are substantial.  Form 1065 can only be prepared using Turbotax Business, this is a separate program from Home&Business or Self-Employed and is only available to install on a PC, there is no Mac or Online version.