A5513: The Complete Guide to Medicare Billing for Custom Diabetic Insoles

A5513 is the HCPCS code Medicare uses for custom-fabricated diabetic inserts. It's one of the most commonly billed DME codes in podiatry, and one of the most frequently denied. The rules are specific, the documentation requirements are strict, and the difference between a clean claim and a denied claim is usually one missing signature on one specific form.

This guide walks through what A5513 actually covers, who qualifies, what documentation you need, and the most common reasons claims get kicked back.

Important: This article provides general educational information about Medicare billing for A5513. It is not legal, billing, or coding advice. Medicare policy changes frequently. Always verify current LCDs, fee schedules, and your MAC's specific guidance before submitting claims. Consult a qualified billing professional for your specific practice situation.

What A5513 actually is

A5513 is the HCPCS code for a custom-fabricated, multi-density insert for use with a therapeutic shoe for persons with diabetes. The key word is custom-fabricated, meaning the insert is individually molded or milled to a model of the specific patient's foot. It is not pulled from a drawer of sizes.

The code you don't want to confuse it with is A5512, which covers pre-fabricated multi-density inserts that are directly molded to the patient's foot (for example, heat-moldable EVA). A5512 is cheaper, easier to document, and reimburses at a lower rate. Separately, L3000 covers custom-molded foot inserts outside the diabetic shoe benefit, we cover that one in detail in L3000 Custom Foot Orthotic: When It's Payable, When It Isn't.

Quick distinction: A5512 = pre-fab insert, direct-molded to the foot. A5513 = custom-fabricated insert from a model of the patient's foot (scan, cast, or impression).

The Therapeutic Shoe Bill (TSB)

Both A5512 and A5513 live under the Medicare Therapeutic Shoe Bill, a specific benefit created in 1993 for diabetic patients at risk of foot complications. The TSB covers one of two things per calendar year:

• One pair of depth shoes and three pairs of multi-density inserts (the most common arrangement), or
• One pair of custom-molded shoes and two pairs of multi-density inserts (for patients whose feet can't be fit with off-the-shelf depth shoes)

The TSB is a DMEPOS benefit, meaning the billing runs through the DME MAC, not the Part B carrier. That's an important distinction because the documentation rules are stricter than standard Part B office billing.

Qualifying diagnoses

To bill A5513 (or A5512), the patient must have diabetes mellitus (type 1 or type 2) as documented by the certifying physician. That's the baseline. On top of diabetes, the patient must also have at least one of six qualifying foot conditions:

1. Previous amputation of the other foot, or part of either foot
2. History of previous foot ulceration of either foot
3. History of pre-ulcerative callus of either foot
4. Peripheral neuropathy with evidence of callus formation of either foot
5. Foot deformity of either foot
6. Poor circulation in either foot (peripheral arterial disease)

At least one of those conditions must be documented in the certifying physician's medical record, not just on the CMN. This is one of the most common reasons claims get denied on audit: the supplier bills A5513, the MAC pulls the chart, and the certifying physician's notes don't mention any of the six conditions.

The three roles in a compliant claim

A5513 billing involves three separate clinical roles, and understanding how they fit together is critical.

1. The certifying physician

The doctor managing the patient's diabetes. This is usually an MD or DO in primary care, endocrinology, or internal medicine, not the podiatrist who makes the shoes. The certifying physician signs a statement confirming the patient has diabetes, meets the qualifying conditions, and needs therapeutic footwear.

2. The prescribing physician

A physician or non-physician practitioner (including podiatrists) who writes the actual order for the shoes and inserts. The prescribing physician and certifying physician can be the same person only in limited cases.

3. The supplier

The practice or DMEPOS supplier that dispenses the shoes and inserts, often a podiatrist or pedorthist. The supplier must be enrolled with Medicare as a DMEPOS supplier and must perform an in-person evaluation and fitting.

When all three roles are documented properly, the claim is clean. When the certifying physician's notes are thin, the order is missing a date, or the supplier didn't perform an in-person fitting, the claim is at risk.

Documentation requirements

Here's the checklist the DME MAC looks for when adjudicating or auditing an A5513 claim:

• Certification of need: Signed and dated by the certifying physician, confirming diabetes and at least one of the six qualifying conditions
• Detailed written order: From the prescribing physician, including patient name, date, shoe and insert description, and physician signature
• Certifying physician's medical records: Must independently document the diabetes diagnosis and the qualifying foot condition (not just the CMN)
• In-person evaluation note: Supplier's documentation of the foot evaluation and measurement
• Proof of delivery: Signed by the patient, with the date the shoes and inserts were actually dispensed
• Model/scan documentation: For A5513 specifically, proof that a model of the patient's foot was used (scan file, impression, or cast)

The three-pair rule

Under the TSB, Medicare covers up to three pairs of A5513 (or A5512) inserts per calendar year for a patient using depth shoes. The three pairs can be dispensed all at once or staggered throughout the year. Patients in custom-molded shoes (A5501) are limited to two pairs per year.

Some practices make the mistake of dispensing all three pairs on day one and then never seeing the patient again. That's technically allowed, but it leaves clinical follow-up on the table and makes audit response harder. A better practice is to dispense the first pair at fitting, the second at a 3 – 4 month check-up, and the third later in the year, each with a chart note documenting the encounter.

Reimbursement rates, check your DME MAC

A5513, A5512, and A5500 reimbursement amounts vary by year, by jurisdiction, and by your specific DME MAC. The Medicare DMEPOS fee schedule is updated quarterly and the current numbers should be pulled from your MAC's current fee schedule rather than from any blog post (including this one). Historic CMS publications and the CMS DMEPOS fee schedule page are the canonical sources.

Two things worth knowing about how the codes are paid that don't change with the fee schedule:

• A5513 is billed per insert, not per pair. A patient receiving three pairs of inserts in a calendar year generates six units of A5513. The Therapeutic Shoe Bill annual cap is three pairs of inserts (six units), one pair of shoes.
• A5513 reimburses higher than A5512 because it requires a custom-molded device. The custom-molded build needs to be defensible in your documentation, or the auditor may downcode the claim to A5512.

Common denial reasons (and how to avoid them)

1. Certifying physician's records don't document the qualifying condition

The #1 reason A5513 claims get denied on audit. The CMN is signed, but when the auditor pulls the certifying physician's chart notes, they don't mention neuropathy, deformity, or any other qualifying condition. Fix: Before submitting, verify the certifying physician's notes contain the diagnosis language. If not, request an updated note.

2. Missing in-person evaluation

The supplier must perform and document an in-person foot evaluation. A scan file alone isn't enough, you need a chart note describing the encounter. Fix: Create a template evaluation note that covers foot inspection, risk assessment, and measurement.

3. Claim for custom-fabricated without proof of a model

A5513 requires that the insert be fabricated from a model of the patient's foot. If the supplier can't show a scan file, cast, or impression, the claim can be recoded to A5512 on audit. Fix: Keep the scan or impression file in the patient chart with a timestamp.

4. Delivery documentation missing

No proof of delivery, no payment. The patient has to sign for the shoes and inserts, and the date has to be documented. Fix: Have a standard delivery ticket signed at every fitting.

5. Wrong prescriber type

The order must come from a physician or qualifying non-physician practitioner. A "prescription" from a pedorthist doesn't count. Fix: Make sure the detailed written order is signed by an MD, DO, PA, or NP.

How central fabrication fits a compliant workflow

A central fabrication partner can produce A5513-compliant inserts as long as the clinical documentation lives with the supplier. Here's what a clean workflow looks like:

1. Initial visit: Supplier performs in-person evaluation, scans the patient's feet, documents risk factors and qualifying condition, collects the certifying physician's statement
2. Prescribing order: Written order on file from the prescribing physician
3. Fabrication: Scan file sent to central fab, which mills a custom multi-density insert from the model, satisfying the "custom-fabricated from a model" requirement
4. Delivery visit: Supplier fits the insert into the therapeutic shoe, confirms fit, and captures signed proof of delivery
5. Claim submission: A5513 billed per insert, with all documentation retained for potential audit

Whether you mill the insert in-house or send the scan to a central fab, the Medicare requirements are the same. The supplier owns the compliance, the fabrication method just has to meet the "custom-fabricated from a model" definition.

Bottom line

A5513 isn't hard to bill cleanly, but it's easy to bill sloppily. The claims that survive audit all have the same thing in common: a paper trail that a reviewer can follow from diagnosis to order to fitting to delivery, with every signature in place. Build that workflow once, make it a standard operating procedure, and A5513 becomes one of the most reliable revenue streams in a diabetic-focused practice.

Remember: Medicare LCDs and fee schedules change. Always check current guidance from your DME MAC and consult a qualified billing professional before adopting any specific billing workflow.