How to edit a signed PDF on iPhone without breaking it

The lease is signed, the landlord's signature is on page 2, and you notice the move-in date is blank. Or the freelance contract came back signed with your rate typed as $45 instead of $54. You need to know how to edit a signed PDF on your iPhone, and whether you can edit signed PDF files at all without breaking the agreement.

Why editing a signed PDF is tricky

Editing a signed PDF is easy or impossible depending on what kind of signature sits on the page. Most signatures in everyday PDFs are pictures of handwriting; a few are cryptographic seals over the whole file. The two can look alike on screen and behave in opposite ways when you change anything.

The law can treat both as signatures. The US ESIGN Act defines an electronic signature as "an electronic sound, symbol, or process, attached to or logically associated with a contract or other record" that a person adopts with the intent to sign. A finger-drawn signature on a PDF fits that idea, yet it is not a digital signature in the technical sense.

Two kinds of signature: a drawing and a seal

A drawn signature is an image placed on the page, like a stamp. The PDF around it is an ordinary file, and you can add text, initials or a page without touching the image. Wikipedia's electronic signature article calls electronic signatures "a legal concept distinct from digital signatures, a cryptographic mechanism," and notes one can be as simple as a typed name.

A certificate-based digital signature is a seal over the content of the file. Wikipedia's digital signature article says such a signature is "mathematically bound to the content of the message," and that nobody can change even a single digit without making the verification fail. The guide to electronic vs digital signatures explains the difference in more depth.

How to edit a signed PDF on iPhone, step by step

Editing a signed PDF with a drawn or scanned signature takes seven steps on iPhone, once you and the other party agree on the change. MRS places text, drawings, images and signatures as separate marks on top of the page, so the signature and the printed text underneath stay as they were.

1. Save the PDF to Files. In Mail or Messages, open the attachment, tap the Share button, then tap Save to Files and pick a folder. MRS does not appear as an Open In target in other apps, so the file goes through Files first.
2. Import it into MRS. Tap Import file and choose the PDF. MRS keeps the file exactly as it came until you edit and save it, and the copy in Files stays your record of the signed version.
3. Add the missing text. Tap Text, tap the page where the date or word belongs and type. Pick the font closest to the document from 7 fonts, such as Times New Roman for a typed contract, set a size from 12 to 48 and pick black from the color row.
4. Initial the change. Tap Sign and draw your initials with a finger in black or blue ink, then place them next to the new text and resize them to fit. MRS keeps your newest 5 signatures, so the next set of initials takes two taps.
5. Or add an addendum page. For a new clause or a second signer, open the editor's menu and tap Add Empty Page; MRS adds it after the last page. Type the addendum on it, then have every party sign that page.
6. Close the editor and check the result. MRS saves the file when you leave the editor. Open the document again and zoom in on each change: placed signatures can still be moved and resized, and the eraser can still remove marks it touches.
7. Send it back. Share the corrected PDF by Mail or Messages with one line that lists each change, so the other party can confirm it. The guide on how to save a PDF on iPhone shows where to keep both versions.

The part people get wrong: fixing the old text

The most common mistake is trying to rewrite a word that is already printed in the signed PDF. MRS does not edit the original text of a PDF; it adds new marks on top. That limit suits signed documents: the agreed text stays readable, and your correction sits next to it with your initials.

To fix a typo such as $45, draw a single line through it with the Draw tool, type $54 beside it and add both parties' initials. Never cover the old value with a white box, because a hidden change on a signed contract looks like tampering even when it is not.

Drawn signature vs digital signature vs signed paper scan

The type of signature decides what you can change, what breaks and what to do next. A scan of a paper contract that someone signed in ink behaves like a drawn signature: the whole page is a picture.

Which one you have

You can tell the kinds apart in a minute. Open the PDF in Adobe Acrobat Reader on a computer: a certificate-based signature shows a panel at the top with a status, and clicking the signature opens its certificate details.

A drawn signature shows no panel at all. If the sender used an e-signature service, ask them; they can tell you whether the file carries a certificate seal.

Tips for a change everyone can trust

A clean change is visible, initialed and dated. These habits keep a corrected contract easy to check for everyone who signed it.

• Strike, do not hide. Draw a single line through the old value so it stays readable, then write the new value next to it.
• Initial every change. Each party puts initials next to each change, not only on the last page.
• Date the change. Add the date next to the initials, for example "Oct 29, 2026".
• Match the font. Times New Roman at size 12 sits well on most typed contracts; Helvetica suits forms printed in a plain sans-serif font.
• Keep the original. Leave the signed file untouched in Files and give the edited copy a new name, such as "Lease Oak St signed + addendum".

A rule for bigger changes: use an addendum page

An addendum page is the clean route for anything longer than a date or a number. Title the page "Addendum 1", name the original document and its date, write each change as a numbered item and leave a signature line and a date line for every party.

The original pages stay exactly as they were signed, and the new page carries its own signatures. The guide to signing a PDF on iPhone covers how to place each signature on the page.

How to check the edited PDF

Check the file before you send it, because the other party will read it on a different screen. Run these tests on the copy you are about to share.

• Zoom test: Is each change readable at full size? Zoom into every added date, word and set of initials.
• Position test: Does the new text sit on its line? A date that floats above the line looks careless on a lease.
• Original test: Is the signed text still visible? Every printed word and the original signatures must still show.
• Second viewer test: Does the file look the same in another app? Open the shared copy in Files or Books on the iPhone before you send it.
• Signature panel test: If the file had a digital signature, does Acrobat flag it? Expect a changed or invalid status, and plan the re-sign.

A workable test before you hit send

Send the edited PDF to yourself first. Open the email on another device and read every page once; if the other party has to sign the addendum, check that their signature line is empty and easy to find.

Common mistakes and edge cases

Most problems with a signed PDF come from hidden changes or from the wrong kind of file. Each one has a short fix.

• Mistake: changing a signed contract quietly. The other party did not agree to the new text, and the change can cause a dispute. Ask first, then initial the change or add a signed addendum.
• Mistake: covering old text with a white box. The change looks like tampering. Strike the old value through and write the new one beside it.
• Mistake: editing the only copy. You lose the version everyone signed. Keep the original untouched in Files and edit a renamed copy.
• Mistake: expecting to fill form fields. MRS places text on top of the page and does not fill interactive form fields. Tap Text and place your entry over the field box instead.

Edge case: a PDF with a digital signature

A certificate-signed PDF cannot take an edit and keep a valid signature, in MRS or in any other editor. Saving any change writes a new version of the file, and the signature was calculated over the old one, so viewers show it as invalid or changed.

Your options are to ask the sender for the unsigned file, or to ask the signer to sign the corrected version. If the document was certified rather than signed, the certifier may have allowed some actions, such as filling in fields or adding comments; the sender can tell you which ones. People often search for how to edit a signed PDF without removing the signature, and for a digital signature only a new signature fixes it.

The US ESIGN Act also says it does not "require any person to agree to use or accept electronic records or electronic signatures". If the other party wants a fresh certificate signature or a paper copy, that is their call.

Your signed PDF checklist and next steps

Run through these points before you change any signed PDF.

• Type: check whether the signature is a drawing or a certificate seal.
• Agreement: get the other party's agreement to the change before you make it.
• Original: keep the signed file untouched and edit a renamed copy.
• Change: strike the old value, add the new one, and initial and date it.
• Addendum: put new clauses and new signers on a dated page that every party signs.

Drawn signatures, initials and addendum pages are everyday PDF edits, as the PDF editing basics on mobile show. Download MRS to add text, initials and blank pages to a PDF on your iPhone, with your newest 5 signatures saved for two-tap reuse; MRS runs on iPhone with iOS 16 or later. Questions about the app go to MRS support.