| G44 | Other headache syndromes | NON-BILLABLE CODE |
| G44.0 | Cluster headaches and other trigeminal autonomic cephalgias (TAC) | NON-BILLABLE CODE |
| 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 |
| G44.1 | Vascular headache, not elsewhere classified | BILLABLE CODE |
| G44.2 | Tension-type headache | NON-BILLABLE CODE |
| G44.20 | Tension-type headache, unspecified | NON-BILLABLE CODE |
| G44.201 | Tension-type headache, unspecified, intractable | BILLABLE CODE |
| G44.209 | Tension-type headache, unspecified, not intractable | BILLABLE CODE |
| G44.21 | Episodic tension-type headache | NON-BILLABLE CODE |
| G44.211 | Episodic tension-type headache, intractable | BILLABLE CODE |
| G44.219 | Episodic tension-type headache, not intractable | BILLABLE CODE |
| G44.22 | Chronic tension-type headache | NON-BILLABLE CODE |
| G44.221 | Chronic tension-type headache, intractable | BILLABLE CODE |
| G44.229 | Chronic tension-type headache, not intractable | BILLABLE CODE |
| G44.3 | Post-traumatic headache | NON-BILLABLE CODE |
| G44.30 | Post-traumatic headache, unspecified | NON-BILLABLE CODE |
| G44.301 | Post-traumatic headache, unspecified, intractable | BILLABLE CODE |
| G44.309 | Post-traumatic headache, unspecified, not intractable | BILLABLE CODE |
| G44.31 | Acute post-traumatic headache | NON-BILLABLE CODE |
| G44.311 | Acute post-traumatic headache, intractable | BILLABLE CODE |
| G44.319 | Acute post-traumatic headache, not intractable | BILLABLE CODE |
| G44.32 | Chronic post-traumatic headache | NON-BILLABLE CODE |
| G44.321 | Chronic post-traumatic headache, intractable | BILLABLE CODE |
| G44.329 | Chronic post-traumatic headache, not intractable | BILLABLE CODE |
| G44.4 | Drug-induced headache, not elsewhere classified | NON-BILLABLE CODE |
| G44.40 | Drug-induced headache, not elsewhere classified, not intractable | BILLABLE CODE |
| G44.41 | Drug-induced headache, not elsewhere classified, intractable | BILLABLE CODE |
| G44.5 | Complicated headache syndromes | NON-BILLABLE CODE |
| G44.51 | Hemicrania continua | BILLABLE CODE |
| G44.52 | New daily persistent headache (NDPH) | BILLABLE CODE |
| G44.53 | Primary thunderclap headache | BILLABLE CODE |
| G44.59 | Other complicated headache syndrome | BILLABLE CODE |
| G44.8 | Other specified headache syndromes | NON-BILLABLE CODE |
| G44.81 | Hypnic headache | BILLABLE CODE |
| G44.82 | Headache associated with sexual activity | BILLABLE CODE |
| G44.83 | Primary cough headache | BILLABLE CODE |
| G44.85 | Primary stabbing headache | BILLABLE CODE |
| G44.86 | Cervicogenic headache | BILLABLE CODE |
| G44.89 | Other headache syndrome | BILLABLE CODE |
