S66.399Header code — not billable

Other injury of extensor muscle, fascia and tendon of unspecified finger at wrist and hand level

Short description: Inj extensor musc/fasc/tend unsp finger at wrs/hnd lv

Chapter
19. Injury, poisoning and certain other consequences of external causes
Category
S66
Effective date
October 1, 2026

Related codes in category S66

S66Injury of muscle, fascia and tendon at wrist and hand levelS66.0Injury of long flexor musc/fasc/tend thumb at wrs/hnd lvS66.00Unsp inj long flexor musc/fasc/tend thumb at wrs/hnd lvS66.001Unsp inj long flexor musc/fasc/tend r thm at wrs/hnd lvS66.001AUnsp inj long flxr musc/fasc/tend r thm at wrs/hnd lv, initYesS66.001DUnsp inj long flxr musc/fasc/tend r thm at wrs/hnd lv, subsYesS66.001SUnsp inj long flxr musc/fasc/tend r thm at wrs/hnd lv, sqlaYesS66.002Unsp inj long flexor musc/fasc/tend l thm at wrs/hnd lvS66.002AUnsp inj long flxr musc/fasc/tend l thm at wrs/hnd lv, initYesS66.002DUnsp inj long flxr musc/fasc/tend l thm at wrs/hnd lv, subsYesS66.002SUnsp inj long flxr musc/fasc/tend l thm at wrs/hnd lv, sqlaYesS66.009Unsp injury of long flexor musc/fasc/tend thmb at wrs/hnd lv

Frequently asked questions

What is ICD-10 code S66.399?

S66.399 is an ICD-10-CM diagnosis code for Other injury of extensor muscle, fascia and tendon of unspecified finger at wrist and hand level.

Is S66.399 a billable code?

No. S66.399 is a category/header code, not billable on its own — use one of its more specific child codes instead.

What ICD-10-CM chapter is S66.399 in?

S66.399 falls under Chapter 19: Injury, poisoning and certain other consequences of external causes.

When did S66.399 become effective?

S66.399 has been effective since October 1, 2026, per the CMS/CDC ICD-10-CM annual release.

What other codes are related to S66.399?

S66.399 belongs to category S66, which includes 12 other codes — see the related codes list on this page.

ICD-10-CM data maintained by CDC/CMS (public domain). Always verify codes with authoritative sources before making coding or billing decisions.