Certain back-to-school purchases, such as clothing, school supplies, computers, and other items as defined by the statute, are exempt from sales tax for this time period only.
This includes clothing $100 or less; school supplies not to exceed $50 per purchase; software $350 or less; computers not to exceed $1,500 and graphic calculators not over $150.
More information can be found on the DOR website https://dor.mo.gov/