Overview

Sole proprietorships represent one of the most challenging business types to verify because they are often not required to register with the Secretary of State. Unlike corporations or LLCs, sole proprietors typically operate under the owner's personal identity, making traditional KYB verification difficult or impossible.

Key challenges for sole proprietor verification:

No formal registration: Most sole props lack Secretary of State registrations
Limited public records: Minimal official documentation to verify against
Mixed identity: Business and personal identity often intertwined
Verification gaps: Standard KYB processes fail or return low-confidence matches

Despite these challenges, sole proprietors are legitimate businesses that need access to financial services, marketplace platforms, and business tools. This guide provides a comprehensive verification workflow that combines TIN validation, online presence analysis, and individual verification to assess sole proprietor applications with confidence.

Identifying Sole Proprietorships

Before routing an application to sole proprietor verification, you need to determine if the business is actually a sole prop. There are two primary identification methods:

Method 1: Self-Identification (Recommended)

Allow applicants to self-identify as sole proprietors during onboarding. This is the most efficient approach and sets appropriate expectations for the verification process.

Implementation:

// During application intake
business_type = applicant_input.business_structure

IF business_type == "SOLE_PROPRIETORSHIP":
    route_to = "SOLE_PROP_VERIFICATION"
ELSE:
    route_to = "STANDARD_KYB"

Method 2: Detection via Business Search Results

If you run a standard business search first, certain response patterns indicate a sole proprietorship:

// After running POST /searches
search_result = response

// Extract key signals
business_id = search_result.business.id
tin_matched = search_result.tin_matched
kyb_rating = GET_RATING(search_result.scores, type="kyb")

// Identify sole prop patterns
IF business_id == NULL AND tin_matched == TRUE:
    // No SoS registration found, but IRS confirms TIN
    route_to = "SOLE_PROP_VERIFICATION"
    reason = "No business registration found, TIN validates - likely sole proprietor"

ELSE IF kyb_rating IN ["C", "F"] AND tin_matched == TRUE:
    // Low confidence registration match, but IRS confirms TIN
    route_to = "SOLE_PROP_VERIFICATION"
    reason = "Low confidence registration, TIN validates - verify as sole proprietor"

ELSE:
    // Standard registered business
    route_to = "STANDARD_KYB"

Detection signals:

No match + TIN valid (business_id == null AND tin_matched == true): Classic sole prop pattern
Low confidence + TIN valid (kyb_rating = C or F AND tin_matched == true): Possible sole prop or data quality issue

Note: C and F ratings indicate low confidence in the registration match. When combined with positive TIN validation, this often suggests a sole proprietorship operating without formal registration.

Verification Workflow Overview

A typical sole proprietor verification flow includes four key stages:

Identification: Determine if the business is a sole proprietor (Self-identification or Baselayer)
TIN Verification: Validate Tax ID with IRS (Baselayer)
Web Presence Review: Assess online credibility and industry (Baselayer)
Individual Verification: Verify the business owner's identity (Partner/s)

Each stage uses a combination of Baselayer endpoints or third-party verification tools to build a complete verification picture despite limited public records.

Step 1: Route Identification

Purpose: Determine whether to verify the applicant as a sole proprietor or registered business.

Required Tools

Baselayer: Business Search (optional, if not using self-identification)

Decision Logic

Use either self-identification during intake OR detection via business search results (see "Identifying Sole Proprietorships" section above).

Decision outcomes:

Sole prop identified → Continue to Step 2
Registered business → Use standard KYB workflow

Context

Early identification of sole proprietors streamlines the verification process by avoiding unnecessary friction from failed KYB checks. It also sets proper expectations with applicants about what information you'll need to verify.

Step 2: TIN Verification

Purpose: Validate the individual's Tax Identification Number - usually their Social Security Number (SSN) - with the IRS to confirm their name and tax ID match.

Required Tools

Baselayer: TIN verification

Baselayer Endpoints

Once you've already identified the applicant as a sole prop - we can use a fast, cost-efficient verification.

POST /tin_verifications

This endpoint is ideal when:

Applicant self-identified as sole proprietor during intake
You want to avoid noise from Secretary of State data
You want cost-efficient verification (lower cost than full business search)

Note: For sole proprietors, the TIN may be either their Social Security Number (SSN) or an Employer Identification Number (EIN). Many sole proprietors use their SSN as their business tax ID, but some obtain an EIN for privacy, banking, or employee-related reasons. Baselayer's TIN verification works for both as long as the name submitted is correct.

Verification Logic

// Submit TIN verification request
response = POST /tin_verifications with business name and TIN

// Check TIN match status
tin_matched = response.tin_matched

IF tin_matched == TRUE:
    flag = "PASS"
    reason = "TIN validated with IRS, acceptable for sole proprietorship"
ELSE IF tin_matched == FALSE:
    flag = "RED"
    reason = "TIN does not match business name per IRS records"
ELSE:
    // tin_matched == NULL (IRS outage)
    flag = "YELLOW"
    reason = "TIN validation unavailable (IRS outage)"

Decision outcomes:

TIN validated (tin_matched == true) → Continue to Step 3
TIN failed (tin_matched == false) → Reject application
IRS outage (tin_matched == null) → Manual review or pause per policy

Context

EIN/SSN verification is the cornerstone of sole proprietor verification. Since most sole props lack formal registrations, IRS validation of their Tax ID provides the primary source of truth. A positive TIN match confirms the business exists in federal records and the name matches IRS records.

For IRS outage handling, see IRS Outage Handling Guide.

Step 3: Online Presence Review

Purpose: Evaluate the sole proprietor's credibility through online presence, reviews, social media, and industry classification.

Required Tools

Baselayer: Online Presence (industry prediction, website analysis, social media & reviews)

Baselayer Endpoints

POST /web_presence_requests

Tip: The web presence request has 20-30 second latency. Consider initiating this request early in your workflow (e.g., during Step 1 or 2) to improve applicant experience.

Verification Logic

Contact Details Verification

// Extract contact match signals from top-level /web_presence_requests response
email_match = response.email_match  // EXACT, DOMAIN, NO_MATCH, or null
email_match_sources = response.email_match_sources
phone_number_match = response.phone_number_match  // EXACT, AREA_CODE, NO_MATCH, or null
phone_number_match_sources = response.phone_number_match_sources
business_address_match = response.business_address_match  // EXACT, SIMILAR, CITY, STATE, NO_MATCH, or null
business_address_match_sources = response.business_address_match_sources
business_website_match = response.business_website_match  // boolean or null
business_website_match_sources = response.business_website_match_sources

// Define valid sources (excludes INPUT_WEBSITE since that's not independent validation)
valid_sources = ["FOUND_WEBSITE", "SOCIAL_PROFILE", "REVIEW"]

// Check email validation
IF email_match IS NOT NULL:
    IF email_match == "NO_MATCH":
        flag = "YELLOW"
        reason = "Submitted email not found in any online sources"
    ELSE IF email_match IN ["EXACT", "DOMAIN"]:
        IF NOT ANY(valid_sources IN email_match_sources):
            flag = "YELLOW"
            reason = "Email only found on submitted website, not independently validated"

// Check phone number validation
IF phone_number_match IS NOT NULL:
    IF phone_number_match == "NO_MATCH":
        flag = "YELLOW"
        reason = "Submitted phone number not found in any online sources"
    ELSE IF phone_number_match IN ["EXACT", "AREA_CODE"]:
        IF NOT ANY(valid_sources IN phone_number_match_sources):
            flag = "YELLOW"
            reason = "Phone number only found on submitted website, not independently validated"

// Check address validation
IF business_address_match IS NOT NULL:
    IF business_address_match == "NO_MATCH":
        flag = "YELLOW"
        reason = "Submitted address not found in any online sources"
    ELSE IF business_address_match IN ["EXACT", "SIMILAR", "CITY", "STATE"]:
        IF NOT ANY(valid_sources IN business_address_match_sources):
            flag = "YELLOW"
            reason = "Address only found on submitted website, not independently validated"

// Check website validation
IF business_website_match IS NOT NULL:
    IF business_website_match == FALSE:
        flag = "YELLOW"
        reason = "Submitted website not found in online presence"
    ELSE IF business_website_match == TRUE:
        IF NOT ANY(valid_sources IN business_website_match_sources):
            flag = "YELLOW"
            reason = "Website only found as input, not independently validated"

Note: Contact detail validation is critical for sole proprietors since formal registration data is unavailable. Independent discovery of contact information (on found websites, social profiles, or review platforms) provides strong verification signals.

Industry Screening

// Extract industry prediction from /web_presence_requests response
industry = response.industry_prediction

// Check for prohibited industries
IF industry.keywords CONTAINS ANY prohibited_keyword:
    flag = "RED"
    reason = "Prohibited industry keyword detected"

// Check prohibited NAICS codes with confidence threshold
IF industry.code IN prohibited_naics_list:
    IF industry.accuracy >= 0.75:
        flag = "RED"
        reason = "Prohibited industry with high confidence"
    ELSE:
        flag = "YELLOW"
        reason = "Potential prohibited industry, needs review"

Note: Prohibited keyword and NAICS code lists are proprietary and available to Baselayer customers upon request. Contact your account representative for access.

Website Analysis

// Retrieve website analysis from /web_presence_requests response
website = response.website_analysis
input_website = response.input_website_analysis

// Check website build status for found website
IF website.website_build_status != "active":
    flag = "YELLOW"
    reason = "Found website is not active (status: " + website.website_build_status + ")"

// Check website build status for submitted website
IF input_website IS NOT NULL AND input_website.website_build_status != "active":
    flag = "YELLOW"
    reason = "Submitted website is not active (status: " + input_website.website_build_status + ")"

// Check for website presence
IF website.url == NULL:
    IF business_age >= 6_months:
        flag = "YELLOW"
        reason = "No website found for established business"
    ELSE:
        flag = "PASS"
        reason = "Acceptable for new business"

Note: For extended best practices on website verification and online presence review, see Online Presence: Best Practices.

Social Media & Reviews

// Retrieve social and review data from /web_presence_requests response
social_profiles = response.found_social_profiles  // array of objects
reviews = response.found_reviews  // array of objects

// Filter for high-confidence results only
high_confidence_profiles = FILTER(social_profiles WHERE confidence == "high")
high_confidence_reviews = FILTER(reviews WHERE confidence == "high")

// Check review quality
FOR EACH review_source IN high_confidence_reviews:
    // Basic quality threshold
    IF review_source.volume > 20 AND review_source.rating < 3.0:
        flag = "RED"
        reason = "Poor review rating with sufficient review volume"
    
    // Check review sentiment summary
    IF review_source.summary CONTAINS ["scam", "fraud", "non-delivery", "fake", "never received"]:
        flag = "YELLOW"
        reason = "Review summary indicates negative fraud/delivery patterns"

// Check social media presence for established businesses
IF business_age >= 6_months:
    IF COUNT(high_confidence_profiles) == 0:
        flag = "YELLOW"
        reason = "No high-confidence social media presence for established business"

Note: Social media and review criteria should be adjusted based on your product and risk appetite. The logic above provides a starting framework.

Context

For sole proprietors, online presence verification often provides the strongest available signals since formal registration data is limited. A robust online footprint with consistent contact information, positive reviews, and legitimate social media presence indicates an established, credible business.

Step 4: Individual Verification

Purpose: Verify the identity and compliance status of the sole proprietor owner.

Required Tools

KYC provider (for identity verification and AML screening)

Context

Since sole proprietorships operate under the owner's personal identity, individual verification is essential. Unlike corporations with multiple officers, the sole proprietor's identity IS the business identity, making this step critical for both compliance and fraud prevention.

Baselayer works with hundreds of partners and can recommend ideal providers for every product and case.

Implementation Checklist

Use this checklist to implement the sole proprietor verification workflow:

Setup

Integrate Baselayer API
Integrate KYC/identity verification provider
Request prohibited industry lists from Baselayer representative
Define sole prop identification method (self-identification vs. detection)
Configure IRS outage handling policy

Step 1: Identification

Implement self-identification option in application intake (recommended)
OR implement detection logic using business search results
Set up routing logic to sole prop vs. standard KYB workflows

Step 2: TIN Verification

Implement POST /tin_verifications
Configure TIN validation logic
Set up IRS outage handling

Step 3: Web Presence Review

Implement POST /web_presence_requests endpoint
Configure contact details verification logic
Configure industry screening for prohibited industries
Implement website analysis checks
Configure social media and review verification logic

Step 4: Individual

Implement KYC/identity verification
Configure manual review queues
Set up rejection workflows

For questions about implementation or to request prohibited industry lists, contact your Baselayer account representative.

Best Practices

1. Early Identification

Encourage applicants to self-identify as sole proprietors during intake
This simplifies the workflow and sets proper expectations
Reduces unnecessary friction from failed standard KYB attempts

2. IRS Outage Handling

Monitor for tin_matched = null with IRS outage warnings
Have a contingency process (pause, manual review, or conditional approval)
See IRS Outage Handling Guide for detailed strategies

3. Risk Context Adjustment

TIN validation alone may suffice for lower-risk products
Higher-risk products should require TIN + web presence + strong reviews
Adjust verification requirements based on your risk appetite

5. Monitor and Refine

Track approval rates and fraud outcomes for sole props separately
Tune web presence thresholds based on performance
Adjust industry restrictions as needed for your use case

Summary

Sole proprietor verification requires a different approach than standard KYB due to limited public records. This workflow provides:

Early identification through self-identification or detection patterns
TIN validation as the primary verification anchor
Web presence analysis to assess credibility and industry
Individual verification to confirm owner identity

By combining these verification layers, you can confidently onboard legitimate sole proprietors while maintaining fraud controls and regulatory compliance.