You pasted a list of employee NIKs into Excel. The columns appear normal. However, the last digit of each number has changed to zero, and Excel does not display any warnings.
The limit is 15 digits, not 16
Excel stores numbers according to the IEEE 754 specification, a binary double-precision format used by almost all processors. The consequence is stated plainly in Microsoft's official documentation: Excel's number precision is 15 digits. Numbers in the 16th position and beyond are rounded to zero.
Microsoft explicitly mentions this case with an example of credit card numbers. For numbers with 16 digits or more, you must use text format. The 15-digit limit is not a bug and cannot be adjusted. It is inherent to how numbers are stored.
Two other symptoms go unnoticed. Leading zeros disappear, so 00123 becomes 123. Long numbers change their display to scientific notation, for example, 1.23E+15.
Indonesian numbers that exceed the limit
This is not a fringe case. Three numbers that are routinely typed in the office are already above the threshold.
NIK, 16 digits. According to the Dinas Dukcapil, its composition is 6 digits for the area code, 6 digits for the date of birth, and 4 digits for the system's serial number.
NPWP, 16 digits. PMK Number 112/PMK.03/2022, amended by PMK Number 136 of 2023, both in effect in JDIH, establishes the NIK as the NPWP for individual residents and a 16-digit format for corporate taxpayers and government agencies.
NITKU, 22 digits. The official FAQ from the Directorate General of Taxes states that NITKU consists of 16 digits of the central NPWP plus 6 digits of the branch serial number, and emphasizes that all characters are numeric, with no characters other than numbers.
The last detail is the most dangerous. Because NITKU is purely numeric, Excel treats it as a number, then truncates its last seven digits.
Two popular fixes that still fail
Changing the column format to Text after the data is entered does not restore anything. Microsoft states that this step only applies to numbers typed after the format is set. Numbers that are already corrupted remain corrupted.
Custom number formatting is also not the answer. Microsoft's documentation limits this method to number codes with fewer than 16 digits, so it helps with postal codes and phone numbers, but not with NIK or NPWP.
What really works
- Turn off automatic conversion. Excel for Microsoft 365 and Excel 2024 has an Automatic Data Conversions setting that can disable truncation to 15 digits, removal of leading zeros, and conversion to scientific notation. This is the only way to prevent damage at the application level.
- Import via Power Query, do not double-click on the CSV file. Open the Data tab, select From Text/CSV, enter the Query Editor, mark the identity number column, change its data type to Text, then Close and Load.
- For single entries, type an apostrophe before the number, or format the cell as Text first before entering the data.
Text-type cells can hold up to 32,767 characters, far exceeding the needs of any identity number.
Checking files that have already circulated
Run these three checks on a copy, not on the original file.
=LEN(A2)in the NIK column should return 16. If the result is 16 but the last digit of the entire column is zero, it is not a coincidence.=ISNUMBER(A2)should ideally return FALSE. A TRUE result means the number is stored as a number and has already undergone rounding.- Look for duplicate values. Two different NIKs differing only in the 16th digit will become identical after rounding, and subsequent data merging will count them as one person.
A final warning. The Precision as displayed option does force values to follow the display, but Microsoft emphasizes that this option is irreversible and lost data cannot be recovered. Save a copy before touching it.
The practical conclusion is simple. Excel excels at processing but is less suitable for storing identity numbers that exceed its own precision limits. Treat NIK, NPWP, and NITKU as text from the first row onward.
Sources
- PMK Number 112/PMK.03/2022 on Tax Identification Numbers, status Effective, JDIH BPK
- PMK Number 136 of 2023 on Amendments to PMK 112/PMK.03/2022, status Effective, JDIH Ministry of Finance
- NITKU FAQ Material, Directorate General of Taxes
- Meaning of the 16 Digit Population Identification Number, Dinas Kependudukan dan Pencatatan Sipil Provinsi Kalimantan Barat
- Excel specifications and limits, Microsoft Support
- Keeping leading zeros and large numbers, Microsoft Support
- Floating-point arithmetic may give inaccurate results in Excel, Microsoft Learn