Fill in a PDF form

Three kinds of “PDF form”

Telling them apart explains almost every problem people hit with form tools.

• A real interactive form (AcroForm). It contains actual fields with names. This is what the tool fills, and what most government and business forms use.
• A printed form. Boxes and lines drawn on the page, with nothing to click. Far and away the most common — and no tool can “detect” fields that were never there. Use Create fillable PDF to add them, or Edit PDF to type on top.
• An XFA form. Adobe’s own XML format, which only really works in Acrobat. We will tell you if you have one rather than showing an empty list.

Should you lock the values in?

Locking — flattening, in PDF terms — draws your answers into the page and removes the interactive fields. The text stays selectable and searchable; it simply stops being editable.

Lock it when you are sending the completed form to someone. It renders identically everywhere, and no one can change your answers without it being obvious.

Leave it unlocked when you are saving a draft, or sending a partly-completed form to someone who has to finish it.