# Reformat A Custom Date Field
**URL:** https://community.mp3tag.de/t/reformat-a-custom-date-field/68811
**Category:** Support
**Created:** [June 11, 2025, 2:25am UTC](https://community.mp3tag.de/t/reformat-a-custom-date-field/68811 "2025-06-11T02:25:53Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@cmsylvester](https://community.mp3tag.de/u/cmsylvester)
#### Post date: [June 11, 2025, 2:25am UTC](https://community.mp3tag.de/t/reformat-a-custom-date-field/68811/1 "2025-06-11T02:25:53Z")
I am a frustrated newbie trying to create my first Replace with Regular Expression action. Here is my situation:
Filename: Ozzie And Harriet\_520321\_The Ego Builder.mp3
I have successfully extracted the date from the filename to a custom field %otrdate%.
I want to change the %otrdate% field as follows
520321 to 1952-03-21
I performed the following steps:
- I opened Actions \> Action Group
- Clicked on New to create a new Action Group and named it Test
- I selected Action Type: Replace with regular expression
- I entered the following into the fields
- **Field:** Selected %OTRDATE%
- **Regular Expression:** (\d\d)(\d\d)(\d\d)
- **Replace matches with:** 19$1-$2-$3
- Clicked on OK
- Clicked on OK to save the expression
- I checked on the Test action group to enable it
- I clicked on apply, but I do not see any change.
Since I have yet to do my first successful replacement, I’m not sure what piece I’m missing. I modified another expression to try to accomplish what I wanted, but maybe I have the wrong syntax and it can’t find what I think I’m searching for.
Once I get my first one working, I feel confident that I can modify this one, create other Action Groups to account for other date variations I encounter and then select the one I need for the particular date issue in the file I’m working on.
Any help her will be greatly appreciated!
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### Author:  [@poster](https://community.mp3tag.de/u/poster)
#### Post date: [June 11, 2025, 4:57am UTC](https://community.mp3tag.de/t/reformat-a-custom-date-field/68811/2 "2025-06-11T04:57:53Z")
> [@cmsylvester](#):
>
> **Field:** Selected %OTRDATE%
The field name has to be OTRDATE.
Have a look at your tagfields with the extended tag view (ALT-t). You probaly now have an additional field named %otrdate%.
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### Author:  [@cmsylvester](https://community.mp3tag.de/u/cmsylvester)
#### Post date: [June 11, 2025, 8:49am UTC](https://community.mp3tag.de/t/reformat-a-custom-date-field/68811/3 "2025-06-11T08:49:32Z")
That was it. It works! Once I dropped the % signs from the field name, it worked as expected. Now I have the confidence to create additional actions for other date scenarios.
THANK YOU!
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### Author:  [@system](https://community.mp3tag.de/u/system)
#### Post date: [July 11, 2025, 8:49am UTC](https://community.mp3tag.de/t/reformat-a-custom-date-field/68811/4 "2025-07-11T08:49:45Z")
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