(1) Health care practitioners, other than dentists, shall use the HCFA Form 1500 and instructions provided by HCFA for use of the HCFA Form 1500 when filing claims with issuers for professional services. Health care practitioners that bill patients directly shall provide a properly completed HCFA Form 1500 in addition to any other explanatory information used to bill the patient when requested by the patient. Institutional care practitioners may use HCFA Form 1500 when billing service for employees or as part of outpatient services.

(2) Issuers may only require health care practitioners to use the following coding system for the initial filing of claims for health care services:

(a) HCPCS codes; and

(b) ICD-9-CM codes.

(3) Issuers may only require health care practitioners to use other explanations with a code or to furnish additional information with the initial submission of an HCFA Form 1500 under the following circumstances:

(a) when the procedure codes used describe a treatment or service that is not otherwise classified; or

(b) when the procedure code is followed by the CPT-4 modifier 22, 52, or 99. Health care practitioners may use item 19 of the HCFA Form 1500 to explain multiple modifiers, unless item 19 is used for other purposes in accordance with the instructions for this form.

(4) Health care practitioners may use item 19 of the HCFA Form 1500 to indicate the form is an amended version of a form previously submitted to the issuer by inserting the word "amended" in the space provided.

(5) Health care practitioners billing for services based on the amount of time involved shall define on item 19 the time interval in item 24 G of the HCFA Form 1500, if the time interval is not already defined the HCPCS code. If not defined by either HCPCS or in item 19, units will be assumed to be days of treatment.

(6) Health care practitioners shall provide the unique physician identification number, if assigned by HCFA, in box 17a and either the federal tax identification number or social security number to complete item 25 of the HCFA Form' 1500, as required by the HCFA instructions.