Under the Agriculture Improvement Act of 2018 (commonly known as the “Farm Bill”), hemp and its derivatives are federally legal provided the cannabis plant and its extracts contain no more than 0.3% of Delta‑9 THC by dry weight. Legal Reader+3Wikipedia+3Chronic Guru+3
Because THC-A is an acidic precursor to Delta-9 THC, and not Delta-9 itself, many interpret that hemp-derived THC-A meeting the <0.3% Delta-9 THC threshold can be federally lawful. Chronic Guru+1
That said: heating THC-A converts it into Delta-9 THC (which is psychoactive) and that introduces regulatory risk. WebMD+1

State Variation & Why It’s Complicated

Even though the federal law lays a baseline, state laws vary widely, and for THC-A the situation is especially nuanced. Some states treat hemp-derived THC-A as legal if it meets the hemp threshold; others treat it similar to marijuana/cannabis/Hemp derivatives with stricter controls. IndaCloud+2Friendly Hemp+2
Some of the complexity points:

• States may define “total THC” to include both Delta-9 THC and THC-A (or the conversion into THC) — meaning THC-A counts toward the 0.3% limit. Friendly Hemp

• States may ban “intoxicating hemp derivatives” even if hemp-derived and <0.3% Delta-9 THC. ARCannabisClinic

• Local enforcement and regulatory clarity may lag behind the marketplace.

Examples: Legal & Restricted States

• Some states list THC-A as legal when derived from hemp (<0.3% Delta-9 THC). For instance, one guide says states such as Arizona and Texas permit hemp-derived THC-A under hemp laws. Chronic Guru+1

• On the flip side, several states are cited in sources as restricting THC-A explicitly or having laws that would make its sale/possession problematic. For example: Idaho, Kansas, Nebraska, South Dakota, West Virginia are listed as states where THC-A may be illegal or restricted under certain definitions. IndaCloud+1

What That Means for You

If you’re wondering if THC-A is legal in your state, here are the steps you should follow:

1. Check your state’s hemp/cannabis statute: Look for definitions of hemp, hemp derivatives, THC limits (Delta-9 and total THC), and whether “THC-A” is mentioned or if “total THC” includes THC-A.

2. Check how the state treats heated/activated products: If THC-A is intended to be heated (turning into Delta-9 THC), some states may regulate it more strictly as cannabis.

3. Check for regulatory guidance: Sometimes, even if the statute is vague, your state’s department of agriculture, cannabis commission, or health agency may have guidance or rules regarding THC-A products.

4. Check retail and possession laws: Some states may allow possession but restrict sale, or vice-versa. Others may ban certain forms (e.g., vapes).

5. Stay updated: Cannabis/hemp law is evolving rapidly—what was lawful one year may change the next.

Bottom Line

Yes — it’s possible that THC-A is legal in your state if it is hemp-derived and meets the <0.3% Delta-9 THC threshold and your state law does not impose further restrictions. However — no guarantee. Because state laws vary and some states outright restrict THC-A (or include it under “total THC” limits or regulatory bans), you must check your specific state’s law.