Disclosure: this is a guest post contributed by the JustFill team and mentions their product, JustFill's PDF mail merge.
A vendor ID of 0007 is not an invitation to do arithmetic. It is four characters that need to arrive in the right box on a form.
If you keep a vendor register in Google Sheets and use it to fill a PDF someone else supplied, the risky bit can happen before the PDF tool sees anything. Import the register as numbers and dates, and the values you meant to print may already have changed.
Here is a small handoff test for that job. It uses three fictional vendors, no add-on and no access to your business data. The example is deliberately dull: leading zeros, a comma inside a company name, a zero amount and a missing reference. Those are the records worth trying before the ordinary ones.
Start with a separate handoff sheet
Keep your working register for calculations, dates and reporting. Make a separate export for the exact text that belongs on the form. In that export, one row means one finished document.
The example Google Sheet has six columns: Vendor ID, Vendor name, Postal code, Payment date, Amount and Reference. All records are invented. You can make your own copy; do not replace the public example with real vendor details.
These are the source CSV lines used to build it:
Vendor ID,Vendor name,Postal code,Payment date,Amount,Reference 0007,"Northwind, Demo",02108,2026-09-06,12.50,PO-0042 0042,Synthetic Orchard,00501,2026-09-07,100.00,PO-0043 0103,Example Workshop,10001,2026-09-08,0.00,
The quotes around Northwind, Demo matter. That comma belongs to the name, not between two columns. The final comma matters too: the third record has an empty Reference, not a missing Amount.
Turn off the conversion you do not want
To reproduce the import, save those four lines as a UTF-8 CSV file. Open a new, blank Google spreadsheet and choose File > Import > Upload. Select the CSV.
In the import options, turn off "Convert text to numbers, dates, and formulas." It was checked by default in the test for this article. Use automatic separator detection or choose comma. Replacing the spreadsheet is fine for this new blank test file; do not choose that option on a working register you need to keep.
Import the data, then look at the first record. Vendor ID should be 0007, Postal code should be 02108 and Amount should be 12.50. The date should still read 2026-09-06.
This export is text on purpose. It is not where you should calculate totals or sort dates for a report. Finish those jobs in the working register, decide how the form needs each result printed, then prepare the handoff.
If your source already says 7 because an earlier import discarded the zeros, turning conversion off now cannot tell you whether the original was 07, 007 or 0007. Go back to the source register. Only pad an identifier when its required length is actually known.
Check the file that leaves Sheets
Select the handoff tab and choose File > Download > Comma-separated values (.csv). Open the downloaded file in a plain-text editor, not another spreadsheet application that might interpret the values again.
Compare the actual text with the source above. Check all three records. The second postal code is 00501; the second amount is 100.00; the third amount is 0.00 and its reference is blank. A blank reference and a zero payment amount are different facts. Do not turn both into the same placeholder.
This also catches a surprisingly simple mistake: exporting the wrong tab. A PDF merge needs the handoff table, not the dashboard, totals or notes you happened to be viewing.
For this example, the CSV was imported into Google Sheets with conversion disabled, the saved spreadsheet was reloaded, and the CSV was downloaded through the File menu. The download was then passed through JustFill's local CSV parser. All 18 data values matched the original, including the comma and empty cell. That was a three-record import/export test on September 6, 2026, not a customer case study or a full PDF-generation test.
Then check what lands on the PDF
Exporting the sheet itself as a PDF gives you a picture of the table. Filling an existing vendor form is a different task: its boxes need values from one selected row. A correct CSV alone cannot prove those boxes are mapped correctly.
Before a real run, map the columns to the reviewed fields in the destination tool. Open a preview for each of the three test records and check:
- Is Vendor ID in the vendor box, not the customer box?
- Does 02108 still have five characters?
- Is the date written in the format the form asks for?
- Can you read the complete company name?
Check the generated file as well as the preview. If you change the supplied PDF, review the mapping again. Similar-looking forms can move a box or change what a repeated "Name" label means.
JustFill's PDF mail merge is one option for this last step: upload the PDF and CSV, review the field mapping and records, then download the approved PDFs.
Its free sample is watermarked; clean exports use paid allowances. Processing happens on JustFill servers, so check your organization's rules before uploading business documents.
You can use the same three-row check with a different PDF tool. Keep it beside the recurring workflow, and run it again when you change the export or destination. The useful result is concrete: the vendor called 0007 in your register is still called 0007 on the document.