Copy to subtask Plugin

Copy to Subtask plugin lets you copy the custom field values from parent issue to its subtasks on creation.

There are minor configurations available using which you can limit this functionality to selected issueTypes and Custom Fields. You can also optionally hide the custom fields that are to be copied from the create subtask screen. Without this, the value will be auto populated from the parent on the screen and can then be overwritten!

Checkout the plugin page for details. Btw, if you haven't guessed it yet, the plugin is absolutely FREE!

Copy to Subtask Admin Configuration