Physical Therapy Billing: The Guide to Getting Paid for the Care You Deliver

Evaluation codes and complexity

PT evaluations use 97161 (low), 97162 (moderate), and 97163 (high), with 97164 for re-evaluations. Like OT, complexity comes from history, examination, clinical presentation, and decision making.

Document why the case is complex. A payer reviewing the note should be able to see the reasoning without guessing.

Plan of care certification

For Medicare patients, the physician or qualified provider must certify the plan of care. Missing or late certification is a common reason Medicare claims are denied or recouped later.

Track certification dates in a system that alerts your team before they expire — not after.

The KX modifier and therapy thresholds

Medicare sets an annual therapy threshold for PT and speech combined. Once a patient passes it, claims need the KX modifier to confirm the care is medically necessary and documented as such.

Missing the KX modifier leads to denials. Adding it without supporting documentation creates audit risk. Both problems are avoidable with daily claim review.

Common PT denial reasons

The denials we see most in PT practices:

• Eligibility not verified or coverage changed
• Visit limits exceeded
• Missing or expired authorization
• Incorrect units under the 8-minute rule
• Modifier errors (59, X-modifiers, GP, KX)
• Timely filing missed

Why daily work matters

A denial caught in three days is a quick correction. A denial caught in ninety days might be past appeal limits. Working every account every business day is not a nice-to-have in PT billing. It is the difference between collecting and writing off.