Hi Gareth,
No, there’s no relationship between them. The cost codes list can be edited to whatever you need them to be without the tags being affected.
There currently isn’t a way to auto change tags when a specific tag appears in the software. (i.e. whenever “fix out” appears change it to something else), however there are some methods to change the tags in some areas of the software, which I’ve explained below. Note: Changing tags will affect how the geometry behaves with scenes as each scene is looking for specific tags to turn on/off, so the 
Scene Tool may not work as expected afterwards.
Adjusting Material Tags
Under each material fields there’s an Edit Tag & BOQ Category button which allows you to change the tag of the material (which will affect the geometry it’s assigned to) plus also adjust the category of the material (which changes where it appears in the takeoff). The post below explains what to do & how it works in more detail. Note: This is only for materials.
Layering Section In Dialogs
Some dialogs have a Layering section which allows you to adjust some tags that tool will be using. Note: This is mainly for the tag assigned to the topmost levels of the group/objects.
Manually Change Tags
Note: This method is mainly for components as there’s currently no other way to adjust their tags.
There are two ways this can be done. 1) Go to the Tags section of the Default Tray & change the name of the tag (this will do a blanket change), or 2) Manually clicking into the objects & reassigning the object to a new/different tag. Note: Since these are considered manual changes I recommend only doing this at the end to save any double handling. This is because if the geometry is then adjusted using a PlusSpec tool it’ll revert to the original tag. Also, any new geometry added via PlusSpec tools will also be placed on the original tag.