A school trip form, a club registration, a monthly timesheet from a landlord or an employer: the form comes as a PDF, or on paper, and it wants your name, your address, a few ticks and a date. Printing it, writing on it and scanning it back is slow. This guide walks through the kinds of forms you'll meet, then how to fill out a PDF form on iPhone with Sign Cat, our app for filling and signing PDFs on iPhone.
Two kinds of PDF form
Before you start, it helps to know which kind you have.
- Fillable forms have their own boxes built in: text boxes, tick boxes and round option buttons. When you open one in Sign Cat, these fields show in blue.
- Flat forms are just a picture of the page, like a scan or a form someone exported without fields. Nothing is tappable, so you put your answers on top of the page.
Sign Cat handles both, and you can mix them on one page: type into the form's own fields, then add text, ticks and a date wherever the form has none. Sign Cat fills text boxes, tick boxes and round options. Other field types, such as drop-down lists, and fields the form has locked don't turn blue; put your answer on top with Text instead.
Get the form into Sign Cat
- A PDF in email or Files: tap Open PDF in Sign Cat, or open the PDF, tap Share and choose Sign Cat.
- A paper form: tap Scan, then Scan paper. The camera lets you scan several pages in one go, and each one becomes a page of a new PDF.
- A photo of a form: tap Scan, then From Photos, and pick one or more photos. Each photo becomes a page.
Scanned and photographed forms are flat, so you fill them with the tools below.
Fill in a form's own fields
On a fillable form, the hint at the bottom reads "Tap blue fields to fill."
- Tap a text field and type. If the form limits how long an answer can be, Sign Cat stops at that length.
- Tap a tick box to tick it, and tap again to clear it.
- Tap a round option to choose it. Options in the same group work together, so choosing one clears the others.
What you type and tick is printed into the copy you save.
Fill in a flat form
If a form has no fields, use the tools at the bottom of the screen: Signature, Initials, Date, Text, Tick and Cross. Pick a tool, then tap the page where it goes.
- Text: tap the line, type in the box that appears, and tap Done. To change it later, double-tap it or tap Edit.
- Tick and Cross: these stay on after the first tap, so you can tick a whole column of boxes one tap at a time. Tap the tool again when you're finished. Put the wrong mark in a box? Select it and tap Cross or Tick to swap it.
- Date: tap where the date goes. Sign Cat puts in today's date.
Drag anything to move it. As you drag, it snaps into line with the other things you've placed on the page, which keeps a column of answers neat. Tap Done (the ✓) when it looks right, and Undo at the top takes back the last thing you placed, moved, changed or deleted on the page (not what you typed into the form's own fields). To repeat something, such as the same answer further down, select it and tap Duplicate (under ⋯ if the row is short of room).
Get the date format right
Forms often say how the date should look. Tap a date you've placed and choose Format. There are six: short written (such as "Jun 12, 2026"), long written ("June 12, 2026"), MM/DD/YYYY ("06/12/2026"), DD/MM/YYYY ("12/06/2026"), DD.MM.YYYY ("12.06.2026") and YYYY-MM-DD ("2026-06-12"). The two written formats follow your iPhone's language; the examples are in English.
Sign Cat remembers the format you picked for the next date you place. Before you've picked one, it starts with the order usually used where you live.
Sign the form
Most forms end with a signature. Pick Signature or Initials, tap the line, and you're done. If this is your first time, our guide on how to sign a PDF on iPhone covers making your signature once and what kind of signature it is.
Save it, and fill it faster next time
Tap Save. Saving makes a separate filled copy and leaves your original PDF as it was. Then choose Share PDF, Save to Files or Print. If you leave a form half done, your answers are kept until you come back to it.
Some forms come back every week or month. For those, go to your library, touch and hold a form you've saved, and choose Sign again with same layout. You get a fresh copy of the same form with your text, ticks, signature and form entries where they were, and the dates moved to today. Change what's different this time, then save.
The To sign and Signed filters and the search box in the library help you find a form again.
Sending invoices too?
Forms come in; invoices go out. If you bill for your work, see our guide on how to make an invoice on iPhone.
What it costs
Opening, scanning, filling, signing, saving and sharing are free, with no watermark and no limit on documents. There are no ads, no account, no trial and no subscription. Sign Cat Pro is an optional one-time purchase that adds red, green and purple ink, Rotate for a signature, initials or tick in a sideways box, and Put on every page, so your initials go on every page in one tap. More on the Sign Cat page.
Your documents are kept on your device and in your own backups unless you share, save or print them.
Quick answers
Can I fill out a PDF form on iPhone for free?
Yes. Typing in fields, ticking boxes, adding text and dates, and saving are all free, with no watermark.
What if the PDF has no boxes to tap?
Use Text, Tick, Cross and Date to put your answers anywhere on the page.
Can I fill out a paper form on my iPhone?
Yes. Tap Scan, then Scan paper, and fill in the scanned pages the same way.
Does filling a form change the original PDF?
No. Saving makes a separate copy and leaves the original as it was.
I fill in the same form every month. Do I start over?
No. Touch and hold last month's saved form and choose Sign again with same layout.
Try Sign Cat
Try Sign Cat: free, no watermark, no sign-up → iyio.com/apps/sign-cat