From ECC to S/4HANA: Why Customer and Vendor Data Cleansing Is a Critical Step in Business Partner Creation

In the migration from SAP ECC to SAP S/4HANA, one of the most significant changes is the shift from managing customers and vendors separately to managing them centrally under a single object: the Business Partner (BP).

In ECC, a customer is managed as a Customer and a vendor as a Vendor. In S/4HANA, both are managed under a single BP, where the same Business Partner can hold multiple roles simultaneously, such as Customer, Vendor, FI Data, Sales Data, and Purchasing Data.

This migration creates an opportunity to improve master data quality across the organization, but it also exposes existing issues such as duplicates, invalid tax numbers, incorrect bank accounts, unsuitable G/L accounts, and missing data. Therefore, Data Cleansing before the move to S/4HANA is not merely a technical task; it is a critical prerequisite for project success. 

Why Is Data Cleansing So Important?

Moving from a Separate Structure to a Unified Structure

In ECC, the same business entity may exist as both a customer and a vendor. For example, a company to which the organization sells products and from which it also purchases services. In such cases, the entity may appear in ECC with two different numbers: a customer number and a vendor number.

In S/4HANA, the objective is to manage that entity as a single Business Partner with both customer and vendor roles. If the data is not clean, the system may create duplicate BPs, merge incorrect entities, or stop the conversion process due to CVI (Customer Vendor Integration) errors.

Common Issues Discovered Before Migration

In S/4HANA migration projects, the most common data quality issues include:

Area	Example Issue	Potential Impact
Customer/Vendor Number	Inconsistent length or missing leading zeros	BP mapping or numbering failure
Tax ID / Tax Registration Number	Missing, duplicated, or invalid format	Reporting, tax, and merge issues
G/L Accounts	Reconciliation account does not exist in target system	Failure to create FI data
Bank Accounts	Invalid IBAN or SWIFT	Vendor payment issues
Addresses	Inconsistent country, city, or postal code	Issues with documents, reports, and interfaces
Payment Terms	Code does not exist in S/4HANA	Payment and collection process failures
Duplicates	Same entity exists separately as customer and vendor in ECC	Duplicate BP creation or incorrect merge

Why Is This Especially Critical in S/4HANA?

In S/4HANA, the Business Partner is the central object supporting FI, MM, and SD processes. Therefore, master data must be consistent, complete, and accurate.

For example:

• If the customer's and vendor's Tax Number are identical, they may need to be merged into a single BP.

• If a vendor's IBAN is invalid, payment runs may fail.

• If the Reconciliation Account does not exist in the target system, company code data cannot be created for the customer or vendor.

• If the Account Group is not mapped correctly to a BP Grouping, the CVI process may fail.

• In other words, data quality directly impacts both migration success and day-to-day operations after Go-Live.

The Solution: How to Perform Data Cleansing Correctly

Step 1: Define the Scope

Before starting any cleansing activities, clearly define what is included in the process:

• Active customers

• Active vendors

• Entities that are both customers and vendors

• Blocked customers and vendors

• Vendors with active bank accounts

• Records with open balances

• Data relevant to FI, Purchasing, and Sales

Not every historical record must be migrated to S/4HANA. It is important to decide in advance which data will be migrated, which will be archived, and which require business review.

Step 2: Data Profiling

At this stage, source data is analyzed to identify quality issues.

Recommended checks:

Check Type	What to Verify
Data Completeness	Mandatory fields are populated
Duplicates	Same name, tax number, address, or IBAN
Format Validation	Customer/Vendor Number, IBAN, SWIFT, G/L Account
Validity	Codes existing in the target system
Consistency	Alignment between Company Code, G/L Account, and Payment Terms
Business Risk	Tax, banking, and payment data

The goal is to gain a clear understanding of which records are valid, which can be corrected automatically, and which require business approval.

Step 3: Identify Customers and Vendors That Should Be Merged into One BP

This is one of the most critical activities in the process. Similar names alone are not enough. Multiple fields must be compared together:

Comparison Field	Importance
Tax Number / Tax Registration Number	Primary identifier for entity matching
Customer/Vendor Name	Initial indicator
Address	Additional validation
Bank Account / IBAN	Important financial indicator
Country	Required for tax and banking formats
Phone Number or Email	Supporting information

Step 4: Clean Customer, Vendor, and BP Numbers

During the transition to S/4HANA, attention should be paid to:

• Ensuring there are no Number Range conflicts.

• Adding leading zeros where required.

• Verifying compliance with the required S/4HANA format.

• Mapping each Account Group to the appropriate BP Grouping.

• Defining the correct BP Roles, such as:

  • Customer Financial Accounting

  • Supplier Financial Accounting

Step 5: Clean Tax Data

Tax data is especially sensitive and should be handled carefully.

Verify that:

• Tax Number exists and is valid according to country requirements.

• VAT Registration Number follows the correct format.

• There are no unexplained duplicate tax numbers.

• Tax Category matches the country.

• Withholding Tax data is correct for vendors.

• There are no inconsistencies between customer and vendor tax data when they are expected to be merged into one BP.

Technical fixes such as removing spaces or unnecessary characters can be automated. However, any substantial modification to a tax number must be approved by Finance or Tax departments.

Step 6: Clean G/L Accounts and Reconciliation Accounts

In the Financial Accounting module, every customer and vendor at the Company Code level is assigned a reconciliation account.

This is a critical element for proper General Ledger integration.

Verify that:

• The G/L account exists in the target system for the relevant Company Code.

• The account is appropriate for the entity type (Customer or Vendor).

• Obsolete accounts not available in S/4HANA are not being used.

• The format includes leading zeros where required.

• There is consistency between Account Group, Company Code, and Reconciliation Account.

Step 7: Clean Bank Account Data

Banking data is one of the highest-risk data areas, especially for vendors.

Field	Required Validation
Bank Country	Matches the bank country
Bank Key	Exists and is valid
Bank Account	Correct format
IBAN	Structurally valid
SWIFT/BIC	Correct length and format
Account Holder	Exists and is clearly defined

Step 8: Perform CVI Validation Checks

Before loading or synchronizing data into S/4HANA, ensure that all records are ready for Customer Vendor Integration (CVI).

Key validations:

• Account Group to BP Grouping mapping is completed.

• Number Ranges are correctly configured.

• BP Roles are defined according to business usage.

• Mandatory fields are completed.

• No critical duplicates exist.

• Tax Number, IBAN, and G/L Account are valid.

• Payment Terms exist in the target system.

• Every Customer/Vendor merge has received business approval.

Summary

The move from ECC to S/4HANA fundamentally changes how organizations manage customers and vendors. Instead of two separate master data objects, S/4HANA introduces the Business Partner as a single central object capable of holding both customer and vendor roles.

To ensure a successful migration, a simple technical conversion is not enough. A structured data-cleansing process is required, including duplicate detection, tax number validation, bank account cleansing, G/L account alignment, payment term validation, Account Group to BP Grouping mapping, and CVI readiness checks.

A high-quality Data Cleansing process reduces migration failures, prevents duplicate BP creation, improves payment and collection reliability, and ensures that master data is ready for stable operations after Go-Live.

Ultimately, data cleansing is not just preparation for S/4HANA migration. It is an opportunity to correct years of inconsistencies, strengthen governance and controls, and establish a clean, reliable master data foundation for future business operations.

For more information, please send an email to info@allegropro.co.il