| G44.00 | Cluster headache syndrome, unspecified | NON-BILLABLE CODE |
| G44.001 | Cluster headache syndrome, unspecified, intractable | BILLABLE CODE |
| G44.009 | Cluster headache syndrome, unspecified, not intractable | BILLABLE CODE |
| G44.01 | Episodic cluster headache | NON-BILLABLE CODE |
| G44.011 | Episodic cluster headache, intractable | BILLABLE CODE |
| G44.019 | Episodic cluster headache, not intractable | BILLABLE CODE |
| G44.02 | Chronic cluster headache | NON-BILLABLE CODE |
| G44.021 | Chronic cluster headache, intractable | BILLABLE CODE |
| G44.029 | Chronic cluster headache, not intractable | BILLABLE CODE |
| G44.03 | Episodic paroxysmal hemicrania | NON-BILLABLE CODE |
| G44.031 | Episodic paroxysmal hemicrania, intractable | BILLABLE CODE |
| G44.039 | Episodic paroxysmal hemicrania, not intractable | BILLABLE CODE |
| G44.04 | Chronic paroxysmal hemicrania | NON-BILLABLE CODE |
| G44.041 | Chronic paroxysmal hemicrania, intractable | BILLABLE CODE |
| G44.049 | Chronic paroxysmal hemicrania, not intractable | BILLABLE CODE |
| G44.05 | Short lasting unilateral neuralgiform headache with conjunctival injection and tearing (SUNCT) | NON-BILLABLE CODE |
| G44.051 | Short lasting unilateral neuralgiform headache with conjunctival injection and tearing (SUNCT), intractable | BILLABLE CODE |
| G44.059 | Short lasting unilateral neuralgiform headache with conjunctival injection and tearing (SUNCT), not intractable | BILLABLE CODE |
| G44.09 | Other trigeminal autonomic cephalgias (TAC) | NON-BILLABLE CODE |
| G44.091 | Other trigeminal autonomic cephalgias (TAC), intractable | BILLABLE CODE |
| G44.099 | Other trigeminal autonomic cephalgias (TAC), not intractable | BILLABLE CODE |
