At the end of the month, the accountant asks how much Client A still owes. The sales representative has a rough estimate, the accountant has a different figure, and the assistant’s Excel file shows a third number. This is a familiar scenario for many businesses that manage customer data using multiple disjointed files.
This article by OMN1 Solution takes you from the tools you currently use (Excel) to how to source data legally and when it is time to switch to a CRM system.
What is customer management, and what information should be recorded?
Customer management involves organizing information, interaction history, and transaction records for each client so the entire business can provide consistent care. A basic customer profile should include:
- Basic information: name, company/organization, contact details, and lead source.
- Purchase and interaction history: items purchased, the staff member handling the account, and the date of the last contact.
- Outstanding balance status: amount receivable and payment due date.
- Person in charge and next steps: to ensure follow-ups are not overlooked.
Excel file for managing customer outstanding balances: Structure and basic formulas
For small businesses, an Excel file remains a practical starting point for managing customer outstanding balances. You can arrange the columns as follows: A for Customer Code, B for Customer Name, C for Invoice Number, D for Invoice Date, E for Payment Due Date, F for Invoice Value, G for Amount Collected, H for Amount Receivable, and I for Days Overdue. Three fundamental formulas:
- Outstanding balance (cell H2): =F2-G2
- Days overdue (cell I2): =IF(H2>0, MAX(0, TODAY()-E2), 0)
- Total debt per customer: =SUMIFS(H:H, A:A, "KH001")
Two handy tips: use automatic coloring (conditional formatting) for overdue rows, and categorize debt by age (e.g., 0–30, 31–60, 61–90 days) to prioritize who to contact first. It is best to test these formulas on your actual file before putting them into full use.
When is an Excel file no longer sufficient?
Excel is effective up to a point, but eventually reveals its limitations:
- Multiple users editing simultaneously can easily lead to version conflicts.
- A formula error can propagate throughout the entire workbook unnoticed.
- No audit trail: it is difficult to track who made changes and when.
- Fragmented data: outstanding debt records are in one place while interaction history is elsewhere, preventing a holistic view.
- Data leaves with employees when they resign.
If you encounter two or more of these signs, it is time to consider a CRM system.
How to acquire customer data for free and legally
The most sustainable way to acquire customer data for free is to have customers voluntarily provide their information:
- Forms and landing pages linked to a benefit (e.g., a document, a quote, or a consultation session).
- Useful content (articles, videos) that draws interested prospects to your website and channels.
- Events and webinars: collecting information via registration.
- Referrals from existing customers: asking them to connect you with acquaintances who have a need.
- Social media channels and Zalo OA, allowing customers to initiate contact with you.
What to avoid
- Strictly avoid purchasing contact lists or mass-collecting personal information from unknown sources. The Personal Data Protection Law (Law No. 91/2025/QH15), effective January 1, 2026, grants users rights such as the right to be informed, to consent, to access, to correct, to delete, and to withdraw consent. The Law prohibits the trading of personal data in any form and asserts that personal data is not considered an asset. The maximum penalty for trading violations is ten times the revenue generated from the violation.
- Best practices: clearly state the intended use, include a clear consent checkbox, allow customers to withdraw consent, and use data strictly for the stated purpose.
Migrating from Excel to CRM: 4 steps
- Clean the file: remove duplicates and standardize the formatting of names and phone numbers.
- Select key information for initial migration: customers, transactions, outstanding balances (receivables/payables), and assigned personnel.
- Run systems in parallel for a few weeks to allow the team to adjust before discontinuing Excel usage.
- Integrate with existing accounting or ERP systems to ensure data consistency regarding outstanding balances.
Conclusion
Effective customer management begins with organized record-keeping—even in Excel—and matures as data becomes centralized, access-controlled, and legally sourced. Start with the basics: a clean outstanding balance file and a data collection form that includes consent.
👉 Contact OMN1 Solution today for a consultation on the best roadmap for migrating your business from Excel to a suitable customer management system.
