Here is my understand of the issue, correct me if I'm wrong. Say you have these tags:
Project 1, Task 1 [billable] - 5hrs
Project 1, Task 2 [billable] - 3hrs
Project 2, Task 3 [billable] - 4hrs
Project 2, Task 4 [billable] - 2hrs
Non project work [billable] - 4 hrs

You'd like to split Non project work to the other 4 projects, so that each gets an extra hour?

If this is correct, then you can't do it.
For this to work we would have to somehow know that those are project tags and that there is a special non project tag which should be split over the other project tags. So in other words, we would need to have a structure where you would type your projects, then type your non projects, then somehow tell the app that that non project is work on projects of the day...
I can only think of two solutions:
-you add this manually at the end of the month when you are making timesheets. You see the projects and you add 1/Nth of time to each on N projects.
-you could use export timesheet and create some script which will process this the way you want.

Hi, I have upgraded to the latest manic time and started using the billable tags which are very helpful. However, they don't resolve the issue that I explained in my previous example. Is there any existing or planned capability to handle this scenario?

Hi,
To clarify my feature request see below example:
Lets say everyday I undertake project management tasks that are applicable to all projects I work on that day. The time is still billable, but to multiple projects. I would like to be able to easily split this time across all billable projects I have worked on that day. e.g. Spent an hour managing the days projects X, Y and Z. 20mins is added to those tags for the day for time sheeting purposes.

Thanks, that does help. Unfortunately for me, and fortunately for ManicTime, I will need to pay for an update to receive that feature.

I don't quite follow, but does this help in any way?
http://www.manictime.com/Releases/Version_v3_3#billable-tags