GILLIAN ROSE TIDWELL
NPI 1811820764
Speech-Language Pathologist in Buffalo Grove, IL

NPI Status: Active since June 08, 2026

Contact Information

1371 ABBOTT CT STE A
BUFFALO GROVE, IL
ZIP 60089
Phone: (847) 777-8995

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Newly Listed Provider
This NPI profile has been added to the NPI registry within the last 30 days.

Table of Contents

NPI Profile Information
Primary Taxonomy
NPI Validation
Other Providers Same Location
Frequently Asked Questions

Individual
Female
Speech-Language Pathologist

About GILLIAN TIDWELL

This page provides the complete NPI Profile along with additional information for Gillian Tidwell, a provider established in Buffalo Grove, Illinois with a medical specialization in Speech-language Pathologist. The healthcare provider is registered in the NPI registry with number 1811820764 assigned on June 2026. The practitioner's primary taxonomy code is 235Z00000X. The provider is registered as an individual and her NPI record was last updated June 2026.

NPI: 1811820764
Provider Name: GILLIAN ROSE TIDWELL
Gender: Female
Entity Type: Individual
Location Address: 1371 ABBOTT CT STE A BUFFALO GROVE, IL 60089
Location Phone: (847) 777-8995
Mailing Address: 1371 ABBOTT CT STE A BUFFALO GROVE, IL 60089
Is Sole Proprietor?: No
Enumeration Date: 06-08-2026
Last Update Date: 06-08-2026
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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: Speech-Language Pathologist
Taxonomy Code: 235Z00000X
Type: Speech, Language and Hearing Service Providers
License State: IL
Taxonomy Description: The speech-language pathologist is the professional who engages in clinical services, prevention, advocacy, education, administration, and research in the areas of communication and swallowing across the life span from infancy through geriatrics. Speech-language pathologists address typical and atypical impairments and disorders related to communication and swallowing in the areas of speech sound production, resonance, voice, fluency, language (comprehension and expression), cognition, and feeding and swallowing.

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 1811820764, we treat the final digit (4) 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 56. The final step is to find the difference between that total and the next multiple of ten (60 - 56 = 4).

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 → 2

Pos 4

Unchanged

Pos 5

Doubled → 16 → 1 + 6

Pos 6

Unchanged

Pos 7

Doubled → 0

Pos 8

Unchanged

Pos 9

Doubled → 12 → 1 + 2

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 1 → 2 8 → 16 → 7 0 → 0 6 → 12 → 3

Step 2: Add all digits plus the NPI constant

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

2 + 8 + 2 + 1 + 1 + 6 + 2 + 0 + 7 + 1 + 2 + 24 = 56

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

The next multiple of ten after 56 is 60. The difference is the calculated check digit.

60 - 56 = 4

This NPI is valid

The calculated check digit is 4, which matches the last digit of 1811820764.