I merged a fillable PDF form with other files and the fields stopped working. What should I do?

Why the fields break

A fillable form has two layers: the drawn page with its lines and boxes, and a set of field definitions stored at document level that give each field its name, type and value. Merge PDFs copies the pages into a new file, but the field definitions are not transferred with them. The page shows up, the boxes may still be drawn, but you can no longer type into them and the values you entered may not appear.

It comes up a lot with account opening requests, supplier registration forms and warranty claims that companies send out as fillable PDFs.

The reliable order: fill, flatten, then merge

1. Open the original form in a PDF reader and fill in every field.
2. Save a flattened copy: choose Print, then a printer called 'Save as PDF' or 'Microsoft Print to PDF', which produces a copy with the answers drawn onto the page.
3. Open the new copy and check every answer is visible, especially checkboxes.
4. Add the flattened copy to Merge PDFs with the other documents, put them in order and press 'Merge and download'.

When not to flatten

If the recipient wants the form itself to stay fillable, for example because they read the fields automatically or someone else will complete it, do not merge or flatten it. Send it on its own as it is, and merge the other documents into a second file. Ask if you are unsure; getting it wrong means filling the form in again from scratch.

• Always keep the original filled form, because a flattened copy cannot be edited later.
• If the form needs a digital signature, merging would invalidate that too, so send it separately.
• If printing to PDF is blocked because the file is restricted, ask the sender for an unrestricted copy.