It’s important to use a Jira issue hierarchy which matches the needs of your team.
Limits Of Jira’s Built-in Issue Hierarchy
Jira comes with a built-in hierarchy of Epic Story Sub-task.
Higher level product specs are filled in at the Epic level, which can then be broken down into lower level Stories, and possibly even further to Sub-Tasks.
This is enough hierarchical levels for many teams. Keeping your issue hierarchy limited to Epics, Stories and Sub-tasks means you don’t need to upgrade your Jira plan or use any external plugins.
All of Jira’s built-in reports will be supported by default. You’ll be able to create roadmaps at the Epic level and add Stories to sprints in the way Jira was intended to be used.
Although there isn’t yet a clear way to visualise your issue hierarchy in a tree down to the Sub-task level in Jira’s standard plan, just about everything else you might need is supported out of the box.
But what if your product specs need to be broken down further? Or you’re working in a very large organisation where a new feature can impact many different departments?
You may feel you need extra levels of hierarchy to adequately break down the work.
Some teams may want to add an Initiative or Feature issue type for high level product specs which can be broken down into multiple Epics.
Other teams may want to add Tasks to Stories instead of Sub-tasks so they can add them to their sprints. Some teams may prefer to use Epics as the highest level and create a new Feature issue type between Epics and Stories.
The variations are endless.
So what do you do if your product specs or organisational structure doesn’t fit neatly into Jira’s default issue hierarchy?
There are a couple of good options.
Using Advanced Roadmaps To Create Issue Types Above Epics
The most common way to add an extra level of hierarchy above Epics is to use Advanced Roadmaps.
Advanced Roadmaps is part of Jira Cloud Premium and lets you configure issue types to use above Epics and roadmap at a higher level.

To get started you have to create a new issue type then configure it to sit above Epics in your issue hierarchy.

Once you’ve configured your hierarchy you’ll be able to link Epics to your new issue type (in this case Features) and bring them up in your plans.
Advanced Roadmaps lets you link Epics to parent issues through the “Parent Link” field.
Once linked, you’ll see child Epics displayed inside parent Features similar to the way you see child Stories displayed in Epics.

For many teams this is an extremely useful way to structure your issue hierarchy.
You get to extend your issue hierarchy, visualise it and create roadmaps at a higher level.
But Advanced Roadmaps may not be for every team.
If you want to create extra levels of hierarchy below Epics or use a flexible issue hierarchy instead of a fixed one, Advanced Roadmaps may not be for you.
Advanced Roadmaps doesn’t support creating new issue types below Epics. You can extend your issue hierarchy up, but not down.
If you’re looking to use the Epic Story Task Sub-task hierarchy or Epic Feature Story Task Sub-task hierarchy, Advanced Roadmaps won’t be able to meet your needs.
In addition, Advanced Roadmaps costs $10/user which can be very pricy if you’re working in a large team and have lots of users on your Jira instance.
If you decide to try Advanced Roadmaps, link up your issues but later decide Advanced Roadmaps isn’t for you, you lose all the links between your Epics and their parent issues.
This can be an annoyance for many teams who want to retain their issue hierarchy but don’t necessarily need to be able to visualise it in Advanced Roadmaps.
Using Agile Docs To Extend Your Jira Issue Hierarchy Above Or Below Epics
Another option is to use Agile Docs to create extra levels of hierarchy in your Jira instance.

Like Advanced Roadmaps, it allows you to create extra levels of hierarchy such as Features or Initiatives above Epics.
But unlike Advanced Roadmaps, you can also create levels of hierarchy below Epics and use a flexible hierarchy instead of a fixed one.
To extend your issue hierarchy with Agile Docs you create an issue link type called “Agile Docs Parent”.

This link type lets you specify if an issue is a “parent of” or “child of” another issue. When inside an issue, you’ll be able to link it to any other issue.

When you open Agile Docs you’ll be able to view the hierarchy you’ve created in extension to Jira’s default hierarchy.

This makes it possible to create an Epic Story Task Sub-task issue hierarchy.
Or the Epic Feature Story Sub-Task hierarchy.
You get complete freedom to create any kind of issue hierarchy you like. You can use a different issue hierarchy in every project as Agile Docs doesn’t require you to stick to any specific structure.
Agile Docs lets you visualise your extended issue hierarchy, display any project, release or filter at any level of granularity and display any field you like.
It gives you a mechanism to export your issues to a csv while retaining their hierarchy and track the story point or time progress of each level.
If you ever decide to stop using Agile Docs, you’ll retain the parent-child relationships between issues.
You won’t be able to visualise your complete issue hierarchy in Agile Docs anymore, but inside issues you’ll still be able to see the “parent of” and “child of” links between issues.

At the moment Agile Docs doesn’t support creating a roadmap, so if you need this feature, Advanced Roadmaps may be required.
But Agile Docs also works with Initiatives or Features created in Advanced Roadmaps, so you can use Advanced Roadmaps to create levels above Epics and to create your roadmap, then use Agile Docs to extend your issue hierarchy further by creating levels of hierarchy below Epics.
Choosing The Right Jira Issue Hierarchy
Whether it’s Jira’s built-in issue hierarchy, Advanced Roadmaps, Agile Docs, or a combination of all three, it’s important to use the issue hierarchy which best meets the needs of your team.