SIENNA MENDEZ
NPI 1003623950
Counselor - Mental Health in Seattle, WA

NPI Status: Active since December 13, 2024

Contact Information

5608 17TH AVE NW STE 1668
SEATTLE, WA
ZIP 98107
Phone: (206) 672-3202

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

Individual
Counselor
Mental Health

About SIENNA MENDEZ

This page provides the complete NPI Profile along with additional information for Sienna Mendez, a provider established in Seattle, Washington operating as a Counselor, focusing in mental health . The healthcare provider is registered in the NPI registry with number 1003623950 assigned on December 2024. The practitioner's primary taxonomy code is 101YM0800X with license number MHCA.MC.700878937 (WA). The provider is registered as an individual and their NPI record was last updated April 2026.

NPI: 1003623950
Provider Name: SIENNA MENDEZ
Gender
Entity Type: Individual
Location Address: 5608 17TH AVE NW STE 1668 SEATTLE, WA 98107
Location Phone: (206) 672-3202
Mailing Address: 5608 17TH AVE NW STE 1668 SEATTLE, WA 98107
Mailing Phone: (206) 672-3202
Is Sole Proprietor?: No
Enumeration Date: 12-13-2024
Last Update Date: 04-21-2026
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A mental health counselor like Sienna Mendez provides treatment to individuals, families, couples, and groups for mental and emotional health issues and relationship problems. Mental health counselors treat clients with a variety of conditions, including anxiety, depression, grief, low self-esteem, stress, and suicidal impulses.

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: Counselor Mental Health
Taxonomy Code: 101YM0800X
Type: Behavioral Health & Social Service Providers
License No.: MHCA.MC.700878937
License State: WA

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 1003623950, we treat the final digit (0) 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 50. The final step is to find the difference between that total and the next multiple of ten (50 - 50 = 0).

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 → 0

Pos 4

Unchanged

Pos 5

Doubled → 12 → 1 + 2

Pos 6

Unchanged

Pos 7

Doubled → 6

Pos 8

Unchanged

Pos 9

Doubled → 10 → 1 + 0

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 0 → 0 6 → 12 → 3 3 → 6 5 → 10 → 1

Step 2: Add all digits plus the NPI constant

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

2 + 0 + 0 + 3 + 1 + 2 + 2 + 6 + 9 + 1 + 0 + 24 = 50

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

The next multiple of ten after 50 is 50. The difference is the calculated check digit.

50 - 50 = 0

This NPI is valid

The calculated check digit is 0, which matches the last digit of 1003623950.