If you have a lot of tags defined in Reminders it can take a lot of scrolling through the list to pick a tag from the alphabetized list and assign it to a reminder in iOS or iPadOS.
Here is a workaround that is often quicker.
Assign to the reminder the first tag in the list (or any tag, really). Then:
- Tap the Title line of the reminder. The cursor should show you are now ready to edit the Title.
- Tap the assigned tag. It should be selected now.
- Delete the existing tag. Start typing the first few letters of the tag you actually want to assign. Suggestions should appear. Continue typing until the suggestions include the tag you need.