Ensure you have taskwarrior 2.4.x or higher.

Install using pip:

pip install taskwarrior-time-tracking-hook

And add it to your Taskwarrior hooks:

mkdir -p ~/.task/hooks
ln -s $(which taskwarrior_time_tracking_hook) ~/.task/hooks/on-modify.timetracking

(if ~/.local/bin is not in your path, this last command will not work. In this case, replace $(which taskwarrior_time_tracking_hook) by ~/.local/bin/taskwarrior_time_tracking_hook)

Add the totalactivetime user defined attribute configuration:

task config uda.totalactivetime.type duration
task config uda.totalactivetime.label Total active time
task config uda.totalactivetime.values ''

Add to reports (replace list with whichever report type you want to modify):

task show report.list.labels
    ID,Active,Age,...,Urg
task show report.list.columns
    id,start.age,entry.age,...,urgency

task config report.list.labels 'ID,Active,Age,Time Spent,...,Urg'
task config report.list.columns 'id,start.age,entry.age,totalactivetime,...,urgency'

Use task <TASK ID> start and task <TASK ID> stop to record when you have started and stopped working on tasks.

Tracked time is stored in a task duration attribute named totalactivetime holding the total number of seconds that the task was active.

By default, this plugin allows you to have one task active at a time. You can change this by setting max_active_tasks in taskrc to a value greater than 1.

Delete the hook:

rm ~/.task/hooks/on-modify.timetracking

Remove the User Defined Attribute (UDA) configuration:

task config uda.totalactivetime.values
task config uda.totalactivetime.label
task config uda.totalactivetime.type

Remove the Python program:

pip uninstall taskwarrior-time-tracking-hook