DR. SYDNEY LOUISE MILLS PSY.D.
NPI 1023728276
Psychologist - Clinical in Fairfax, VA

NPI Status: Active since November 29, 2022

Contact Information

11350 RANDOM HILLS RD STE 310
FAIRFAX, VA
ZIP 22030
Phone: (703) 865-4900

NPI Profile Information
Primary Taxonomy
Medicare Participation & PECOS Status
NPI Validation
Other Providers Same Location
Frequently Asked Questions

Individual
Female
Psychologist
Clinical
Opted-Out Medicare

About SYDNEY MILLS

This page provides the complete NPI Profile along with additional information for Sydney Mills, a provider established in Fairfax, Virginia with a medical specialization in Psychologist, focusing in clinical . The healthcare provider is registered in the NPI registry with number 1023728276 assigned on November 2022. The practitioner's primary taxonomy code is 103TC0700X with license number 0810008021 (VA). The provider is registered as an individual and her NPI record was last updated March 2026.

NPI: 1023728276
Provider Name: DR. SYDNEY LOUISE MILLS PSY.D.
Gender: Female
Entity Type: Individual
Location Address: 11350 RANDOM HILLS RD STE 310 FAIRFAX, VA 22030
Location Phone: (703) 865-4900
Mailing Address: 11350 RANDOM HILLS RD STE 310 FAIRFAX, VA 22030
Mailing Phone: (703) 865-4900
Is Sole Proprietor?: Yes
Enumeration Date: 11-29-2022
Last Update Date: 03-18-2026
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A clinical psychologist like Sydney Mills assesses, diagnoses, and treats mental, emotional, and behavioral disorders. Clinical psychologists help people deal with problems ranging from short-term personal issues to severe, chronic conditions. Clinical psychologists interview patients, give diagnostic tests, provide psychotherapy and design behavior modification programs to help patients.

The provider doesn't accept Medicare and has signed an affidavit to be excluded from the Medicare program. If you are a Medicare beneficiary this means a provider can charge whatever they want for services rendered but must follow certain rules to do so. Sydney Mills opted out of Medicare effective on 10-17-2025 until 10-17-2027. Opt out periods last for two years and cannot be terminated unless the provider is opting out for the very first time and the affidavit is terminated no later than 90 days after the opt out effective date. Opt-out affidavits might renew automatically renew every two years. The provider opted out of Medicare and cannot order and refer services to other healthcare providers.

Location Map

Specialty - Primary Taxonomy

The NPI enumerator requires providers to submit at least one taxonomy code. A taxonomy code is a unique 10-character code that describes the healthcare provider type, classification, and the area of specialization. There could be only one primary taxonomy code per NPI record. For individual NPIs the license data is associated to the taxonomy code.

Classification: Psychologist Clinical
Taxonomy Code: 103TC0700X
Type: Behavioral Health & Social Service Providers
License No.: 0810008021
License State: VA
Taxonomy Description: A psychologist who provides continuing and comprehensive mental and behavioral health care for individuals and families; consultation to agencies and communities; training, education and supervision; and research-based practice. It is a specialty in breadth -- one that is broadly inclusive of severe psychopathology -- and marked by comprehensiveness and integration of knowledge and skill from a broad array of disciplines within and outside of psychology proper. The scope of clinical psychology encompasses all ages, multiple diversities and varied systems.

Medicare Participation & PECOS Enrollment Status

What is PECOS?
PECOS is the online Medicare enrollment management system or Provider, Enrollment, Chain and Ownership System. The PECOS system is a database of providers who have registered with CMS as providers or suppliers. PECOS is the primary source of information about verified Medicare professionals. Providers that want to participate in this program need to enroll in PECOS with their NPI number to avoid denied claims.

Opted-Out of Medicare? Yes
Opt-Out Effective Date: 10-17-2025
Opt-Out End Date: 10-17-2027
Eligible to Order and Refer? No

NPI NPI Number Validation

How NPI Validation Works

The NPI validation process uses the ISO-standard Luhn algorithm, a mathematical "handshake", to ensure that a provider's 10-digit ID is authentic and free of common typing errors.

To verify the NPI 1023728276, we treat the final digit (6) as the Check Digit—the target answer we need to reach. The process begins by taking the first nine digits and adding a constant value of 24, which accounts for the "80840" prefix required for all U.S. health identifiers. We then double every other digit starting from the right and sum the individual digits of those results together. For this specific NPI, that total comes to 54. The final step is to find the difference between that total and the next multiple of ten (60 - 54 = 6).

Digit-by-digit view

Use the first nine digits for the calculation. Starting from the right, double every other digit. The last digit is the check digit and is not part of the calculation.

Pos 1

Doubled → 2

Pos 2

Unchanged

Pos 3

Doubled → 4

Pos 4

Unchanged

Pos 5

Doubled → 14 → 1 + 4

Pos 6

Unchanged

Pos 7

Doubled → 16 → 1 + 6

Pos 8

Unchanged

Pos 9

Doubled → 14 → 1 + 4

Check

Target digit

Regular digit Doubled digit Check digit

Step 1: Double every other digit from the right

Starting with the rightmost digit of the first nine digits, double every other value. If doubling creates a two-digit number, add those digits together.

1 → 2 2 → 4 7 → 14 → 5 8 → 16 → 7 7 → 14 → 5

Step 2: Add all digits plus the NPI constant

Add the transformed values, the unchanged digits, and the constant 24.

2 + 0 + 4 + 3 + 1 + 4 + 2 + 1 + 6 + 2 + 1 + 4 + 24 = 54

Step 3: Find the amount needed to reach the next multiple of 10

The next multiple of ten after 54 is 60. The difference is the calculated check digit.

60 - 54 = 6

This NPI is valid

The calculated check digit is 6, which matches the last digit of 1023728276.