How to import CSV into Excel without data corruption
January 11, 2026 • Guide
Importing data shouldn't be a gamble. Yet, double-clicking a CSV file is the #1 cause of data integrity issues in financial reporting. Excel's default behavior modifies your data in ways you might not notice until it's too late.
Common Corruption Types
- Leading Zeros Dropped: ZIP codes (02110) become numbers (2110).
- Scientific Notation: Account numbers become 1.23E+11.
- Date Swapping: 04/05/2023 becomes May 4th instead of April 5th.
- Gene Name Errors: A famous issue where gene names like "MARCH1" were converted to dates.
The Golden Rule: Never Double-Click
The only safe manual way to import a CSV is via Power Query:
- Open Excel blank workbook.
- Go to Data > Get Data > From Text/CSV.
- Do NOT click "Load". Click Transform Data.
- Manually verify the data type of every single column.
- Set IDs, codes, and phone numbers to Text.
- Click "Close & Load".
Automate the Integrity
If you process multiple files a day, the manual method is slow and prone to human error. SterileCSV provides a "drag-and-drop" solution that applies safe defaults automatically.
It acts as a firewall between your raw data and Excel, ensuring that 00123 stays 00123, every single time.