According to the Medicare LMRP:

CPT/HCPCS Codes:

98940 Chiropractic Manipulation
98941 Chiropractic Manipulation
98942 Chiropractic Manipulation
98943 Chiropractic Manipulation
A9170 Non-covered service by Chiropractor (discontinued as of 01/01/2002)

Not Otherwise Classified (NOC): N/A

ICD-9 Codes that Support Medical Necessity:
The level of subluxation must be specified on the claim and must be listed as the primary diagnosis. The neuromusculoskeletal condition necessitating the treatment must be listed as the secondary diagnosis. All ICD-9 diagnosis codes must be coded to the highest level of specificity, (4th or 5th digit).

Primary ICD-9 Diagnosis Code Names of Vertebrae
739.0 Occipitocervical (Occ-C1)
739.1 Cervical (C1-C7)
739.1 C1(Atlas)
739.1 C2 (Axis)
739.2 Dorsal (D1-D12) or
739.2 Thoracic (T1-T12)
739.3 Lumbar (L1-L5)
739.4 Sacrococcygeal (S)
739.5 Pelvis

Secondary ICD-9 Diagnosis
Category I ICD-9 Diagnosis (diagnoses that generally require short term treatment)

307.81 Tension headache
721.0 Cervical spondylosis without myelopathy
721.2 Thoracic spondylosis without myelopathy
721.3 Lumbosacral spondylosis without myelopathy
721.90 Spondylosis of unspecified site without myelopathy
721.91 Spondylosis of unspecified site with myelopathy
723.1 Cervicalgia
724.1 Pain in thoracic spine
724.2 Lumbago
724.5 Backache, unspecified
784.0 Headache

Category II ICD-9 Diagnosis (diagnoses that generally require moderate term treatment)

353.0 Brachial plexus lesions
353.1 Lumbosacral plexus lesions
353.2 Cervical root lesions, NEC
353.3 Thoracic root lesions, NEC
353.4 Lumbosacral root lesions, NEC
353.8 Other nerve root and plexus disorders
719.48 Pain in joint (other specified sites) (must specify spine)
720.1 Spinal enthesopathy
722.91 Other and unspecified disc disorder, cervical region
722.92 Other and unspecified disc disorder, thoracic region
722.93 Other and unspecified disc disorder, lumbar region
723.0 Spinal stenosis in cervical region
723.2 Cervicocranial syndrome
723.3 Cervicobrachial syndrome
723.4 Brachial neuritis or radiculitis, NOC
723.5 Torticollis, unspecified
724.01 Spinal stenosis, thoracic region
724.02 Spinal stenosis, lumbar region
724.4 Thoracic or lumbosacral neuritis or radiculitis
724.6 Disorders of sacrum, ankylosis
724.79 Disorders of coccyx, coccygodynia
724.8 Other symptoms referable to back, facet syndrome
729.1 Myalgia and myositis, unspecified
729.4 Fascitis, unspecified
738.4 Acquired spondylolisthesis
756.12 Spondylolisthesis
846.0 Sprains and strains of sacroiliac region, lumbosacral (joint; ligament)
846.1 Sprains and strains of sacroiliac region, sacroiliac ligament
846.2 Sprains and strains of sacroiliac region, sacrospinatus (ligament)
846.3 Sprains and strains of sacroiliac region, sacrotuberous (ligament)
846.8 Sprains and strains of sacroiliac region, other specified sites of sacroiliac region
847.0 Sprains and strains of other and unspecified parts of back, neck
847.1 Sprains and strains of other and unspecified parts of back, thoracic
847.2 Sprains and strains of other and unspecified parts of back, lumbar
847.3 Sprains and strains of other and unspecified parts of back, sacrum
847.4 Sprains and strains of other and unspecified parts of back, coccyx

Category III ICD-9 Diagnosis (diagnoses that may require longer term treatment)

721.7 Traumatic spondylopathy
722.0 Displacement of cervical intervertebral disc without myelopathy
722.10 Displacement of lumbar intervertebral disc without myelopathy
722.11 Displacement of thoracic intervertebral disc without myelopathy
722.4 Degeneration of cervical intervertebral disc
722.51 Degeneration of thoracic or thoracolumbar intervertebral disc
722.52 Degeneration of lumbar or lumbosacral intervertebral disc
722.81 Post laminectomy syndrome, cervical region
722.82 Post laminectomy syndrome, thoracic region
722.83 Post laminectomy syndrome, lumbar region
724.3 Sciatica