A client sends you a form to complete. A supplier wants a signed acknowledgment. Your bank needs a page initialed and returned. The old routine was print, fill in by hand, sign, scan, and send back a crooked, oversized scan. Most of the time you can do the same thing directly on the PDF: place your text where it belongs, tick the right boxes, draw your signature, and save. This guide walks through that process, and is just as clear about what it doesn't do.
Two kinds of "fillable"
Before you start, it helps to know which kind of PDF you're looking at, because "filling a PDF" can mean two different things.
- A flat PDF. The form is just a printed page turned into a PDF: lines, boxes and labels, with nothing interactive. You can't click into a field because there are no fields. This is the most common case for scanned forms and many documents exported from word processors.
- An interactive form. The PDF contains real form fields (technically called AcroForm fields). Clicking a box lets you type in it, checkboxes toggle, and the values are stored in the field itself.
The method below works by placing content on the page: you put text, checkmarks and a signature exactly where you want them. That works on any PDF, flat or not. It does not read or fill the interactive fields of a form; more on that in the limits section.
What you need before you start
- The PDF itself, up to 50 MB.
- An unlocked file. If the PDF is password-protected, unlock it first. You'll need its password; PDF Protect Plus doesn't crack passwords, it removes protection when you supply the right one.
- The information to enter, ready to copy: names, dates, reference numbers.
- A way to draw your signature: a mouse or trackpad works, a finger on a phone or tablet screen often looks more natural.
How to fill a PDF, step by step
- Open the PDF in the fill tool. In PDF Protect Plus, the document opens on your device; nothing is uploaded.
- Place your text. Add a text item, type the content, then position it on the line or in the box where it belongs. Make sure it fits the space without overlapping the printed labels. Repeat for each field: name, address, date, amount.
- Tick the boxes. Add a checkbox mark and place it over each box that needs to be ticked. Take a moment to zoom in and make sure each mark sits clearly inside its box; a mark halfway between two options is the kind of ambiguity forms are designed to avoid.
- Draw your signature. Draw it in the signature area, then place it on the signature line.
- Review every page. Check spelling, dates and numbers, and look for any field you missed, especially on the last page and on the back of multi-page forms.
- Save. The filled version is saved as a new file. Your original, blank PDF stays untouched, which is handy when the same form comes back next year.
Then protect it before sending
A completed form often contains more personal information than the blank one: a social security number, a date of birth, bank details, a signature. If it's going out by email, it's worth protecting the filled copy:
- Open the filled PDF in the protection tool.
- Choose a strong open password, or let the generator create one (16 to 64 random characters).
- Save the protected copy. The file is encrypted with AES-256.
- Send the PDF by email, and the password by another channel: a text message, a phone call.
Our article on password protecting a PDF without uploading it covers this step in more detail, and the guide to sending a PDF password has templates for the separate message.
The limits, clearly
Filling a PDF this way is meant for everyday paperwork. Some situations call for something else, and it's better to know which before you start.
Interactive form fields are not read or filled
If the PDF has real form fields (AcroForm), the app doesn't detect them or write into them. You can still place your text on top of them visually, and the printed result will look filled. But software that reads the form's data, such as a system that imports values from the fields automatically, won't find your entries in those fields. If the recipient explicitly needs the form fields themselves completed, use a tool that fills interactive forms.
XFA forms are not supported
Some forms, often from government agencies, use an older dynamic format called XFA. These files don't behave like regular PDFs, and some viewers show only a placeholder message instead of the form. They're not supported.
The drawn signature is a visual signature
This is the most important limit. A signature you draw and place on the page is an image of your handwritten signature. It is not a certified or qualified electronic signature: it doesn't include a digital certificate, it doesn't prove your identity cryptographically, and it doesn't make later changes to the document detectable.
For a great deal of routine paperwork, a visual signature is all that's asked for. But when a document requires a certified electronic signature, for example some contracts, regulatory filings or documents where the recipient specifies the signature process, use a dedicated electronic signature service. If you're not sure, ask the recipient what they accept.
Other practical limits
- Files are limited to 50 MB.
- A protected PDF must be unlocked first, with its password.
- Placement is manual: you decide where each item goes, so the final check is yours.
A quick example
Sam Patel, a fictional independent consultant, receives a flat, two-page supplier registration form from a new client. He opens it, places his business name, address and tax number on the printed lines, ticks "sole proprietor" and "invoices by email," draws his signature on the last page, and saves. Because the form includes his bank details, he protects the filled copy with a generated password, emails the PDF, and texts the password to his contact. The blank form stays on his drive for the next client who uses the same template.
Tips for a clean result
- Stay inside the lines. Keep each entry within its space and clear of the printed labels, so it reads as deliberate rather than squeezed in.
- Use the format the form asks for. Dates in the expected order, amounts with or without currency symbols as indicated.
- Sign last. Fill and check everything else first, so the signature goes on a document you've reviewed.
- Keep the blank original. Since every result is a new file, you always have a clean copy to start again from.
- Name the file clearly, without personal data in the file name.
Everything stays on your device
Forms are, by nature, full of personal details. In PDF Protect Plus, filling, signing and protecting all happen on your own device, on Windows, macOS or Android. The documents aren't sent to our servers; the app connects only for account sign-in, licence checks and the subscription. See how local processing works for details.
You can download PDF Protect Plus and fill a test form during the 7-day trial.