Deductions & credits

generally, they're not deductible. however 

Federal Tax Breaks
While there are no federal tax deductions or credits set aside for homeschoolers per se, there are provisions under federal tax law that allow homeschoolers to relieve some of their federal tax burden. One such provision allows you to deduct the costs of certain special education expenses (e.g., specialized tutoring or tuition to pay for specialized instruction) and therapy as a medical expense. This tax deduction is available to those who homeschool, as well as those who do not. For more information, consult IRS Publication 502.

Another federal tax break available to homeschoolers is the charitable contributions deduction. When homeschoolers make cash deductions to nonprofit homeschooling associations or donate used curricula and other materials to nonprofit homeschool organizations, libraries or other such organizations, they can deduct the value of their deduction on their federal taxes on Schedule A. If you plan to deduct charitable contributions, keep thorough records. For additional information, read IRS Publication 526.