The answer to this question is not straightforward.
The producers of THCO, such as Binoid, HHC, and Bearly Legal Hemp Company, say they have the protection of the Farm Bill 2018 since THCO comes from processes that have federally legal hemp plants as the base product. However, even at this, they are still somehow unsure of its legality.
Some experts believe this compound is not legal because the 1986 Federal Analogous Act states that any substance analogous to a Schedule 1 drug would itself qualify as a Schedule 1 drug. Regular THC, which is the base compound for THCO, is a Schedule-1 drug.
You should note that this argument isn’t without fault, as it could also mean delta-8 THC is illegal. However, it’s important to recognize that THCO has not been declared illegal on a federal level and technically complies with the 2018 Farm Bill.
In states where adult-use is legal, most cannabis regulators are turning a blind eye to hemp-derived compounds such as THCO as they do not come under strict regulatory purview. Nevertheless, there is still so much confusion about its future legality.