Auto-updating date fields and why you rarely want one

A PDF can be set up to show today's date every time it's opened. It sounds handy, but on anything that gets signed it quietly rewrites the record: open the form a month later and it claims to be from today. Here's how the automatic date works, the calendar drop-down that is usually the better choice, and how to get a date that is filled in once and then left alone.

How the script worksCalendar drop-downsDates that stay put

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Three ways a date field can behave

Decide before you build the form. The difference only shows weeks later, when someone reopens the file.

1

Updates on every open

A script writes the current date each time the file opens. Fine for an “as of” line on a report, wrong for a signed form.

2

Fills once, then stays

A script fills the field only while it's empty. Once the form is saved with a date in it, the date stops moving.

3

Picked by the person

A field formatted as a date, with a calendar to choose from. Nothing is filled in until someone picks a day.

Updated 28 September 2026 · Written by Joe Farwick, who runs this site

How the automatic date works

PDF forms have no built-in “today” setting. The date comes from a short piece of JavaScript stored inside the file. In Acrobat Pro the usual approach is a document-level script; Adobe's developer guide explains that these scripts are saved in the PDF and run after the document has opened, before the first page-open event. The script writes the current date into the field with Acrobat's util.printd function: util.printd("dd mmmm yyyy", new Date()) gives 28 September 2026, and util.printd("mm/dd/yyyy", new Date()) gives 09/28/2026. The whole script can be one line, added in Acrobat under JavaScript > Document JavaScript: this.getField("Today").value = util.printd("dd/mm/yyyy", new Date()); where Today is the name of the date field.

Because it runs on every opening, the field always shows the day the file is being looked at. That's exactly what the feature promises, and exactly the problem.

Why a date should be a fact, not a formula

The date on a form records something that happened: when it was completed, received or signed. A value that changes on every opening can't record anything. The copy you keep, the copy the other side opens and the copy an auditor opens next year will each show a different day, and none of them has to match the day of signing.

Signatures make it worse. A signature beside a self-updating date appears to have been made on whatever day the PDF is next opened. When the date matters, say for a deadline, a notice period or a price that was valid until a certain day, that's a dispute waiting to happen.

Why it often doesn't work anyway

The script only runs where the viewer runs PDF JavaScript. Acrobat and Reader do, unless someone unticks Enable Acrobat JavaScript in the preferences; Adobe's security guidance describes that switch and says what users see when a document then tries to run a script varies by version. Firefox's built-in viewer only started running JavaScript in PDF forms with version 88. Viewers with partial support or none leave the field showing whatever value was last saved into it.

So the same file can show today's date on your laptop, last month's date on a colleague's phone and a blank box on a printout made from yet another app.

A date that fills once and then stays

If you want the convenience without the rewriting, let the script fill the field only while it's empty. In Acrobat, open the field's Properties, go to the Calculate tab, choose Custom calculation script and add: if (event.value == "") event.value = util.printd("dd/mm/yyyy", new Date()); Calculations run when values on the form change, so the date appears as soon as someone starts filling in the form. After the form is saved with a date in it, later openings leave it alone.

Keep the field editable. Someone may fill in the form on Monday and sign it on Wednesday, and the date beside the signature should be Wednesday.

The date drop-down you may actually want

Many people searching for a date drop-down want a calendar picker, and Acrobat has one built in. Adobe's January 2017 release added a one-click Date field to the Prepare Form tool. It isn't a new field type but a text field whose format is set to Date. When such a field has focus in Acrobat or Reader, an arrow appears; clicking it opens a date picker, and the chosen day is written in the format the form's author picked. Older forms with a date-formatted text field get the picker too.

To set one up, add a text field, open its Properties, choose the Format tab, select the Date category and pick a pattern such as mm/dd/yyyy. The picker belongs to Adobe's software, not to the file, so in other viewers people simply type the date.

Dates that came from Word

Some “automatic” dates start life in Word. Its Insert > Date & Time dialog has an Update automatically checkbox that inserts the date as a field, and Word refreshes it each time the document opens. Save that document as a PDF and the field turns into ordinary text, frozen at whatever date Word was showing when the PDF was made. If a PDF made from a letter template carries an unexpected date, that's a likely reason. Correct it before you sign.

When you need to prove when something was signed

Let something other than the document's own script supply the date: an e-signature platform's signing-date field, a trusted timestamp on a certificate-based signature, or the signer typing the real day. For received, approved or paid marks, a stamp written into the page is enough. The free date stamp on this site draws the date into the page content itself, so every viewer shows the same day.

Sources

Automatic dates: questions

How do I make a PDF show today's date automatically?+

In Acrobat Pro, add a document-level JavaScript that writes util.printd("dd/mm/yyyy", new Date()) into the field. It runs only in viewers that support PDF JavaScript, and it changes every time the file opens.

How do I insert a date drop-down in a PDF?+

Add a text field in Acrobat's form tools and set its format to Date, or use the Date field button. Acrobat and Reader then show a calendar picker when the field is selected.

Why does my PDF show a different date on my phone?+

The date script didn't run in the phone's viewer, so the field shows the value that was last saved into it.

Can SignDatePDF add a self-updating date, and what does it cost?+

No, on purpose: Add Date writes a fixed date into the page, which is what a signed document needs. Trying that out is free, and saving the result needs a plan, €2.99 monthly or €24.99 yearly, cancellable anytime with access until the paid period ends. The date stamp costs nothing.

Where an automatic date goes wrong

Signed forms that re-date themselves

Open a form signed in March in June and the box says June. The signature now sits beside a day it wasn't made.

Viewers that skip scripts

The date only refreshes where the viewer runs PDF JavaScript, so one file can show today, an old date or nothing.

Scripts switched off

Acrobat and Reader have an Enable Acrobat JavaScript preference. Where it's unticked, the script never runs.

Frozen copies

Print or flatten the form and the date freezes on whatever day that happened, which may not be the day anyone signed.

Related guides

A date that stays the date

Open your form above, pick the day with Add Date, and it's written into the page for good.

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