General Database Design Question

Okay, I have my idea of how to do this, but would like to get
experience's idea of how to do this since I am a mere 3.5 weeks into
using SQL.

I am working on a time off tracker for my company. We
have an employee table (employee), a request table(request). Originally
I was told that all vacation is a lump of days and they take time off
and it is subtracted from their vacation time. Now, I am getting told
they can take off vacation, pto, bereavement and possibly more.

I
have a time off table now (time_off) that I made just so I could add
time off types for tracking what time of time off the employee took
based on having one pool of time off. I was thinking I needed to add
another table (tracking) that shows the employee id as a foriegn key to
the employee table then have the table show time off type, accrual rate
(cause some accrue at 2 weeks per year and others at 3 days per year)
and a column for increments cause some they can take in increments of
15 minutes and others half days.

My thought was when I create
a new employee, I have put in what types of time off they are allowed,
what the accrual rates for those are. When they take a day off, put it
in the request field and then when they want to view their available
time off, say for the employee, how many vacation days have they
accrued from the tracking database, minus the days they have taken off,
leaves the number of days they have available.

I would LOVE
and APPRECIATE your input, cause I don't want to go down this path only
to find out I could have / should have done it differently.

One
of the things I haven't really figured out is if they add a new time
off type, how to add it for all the employees and make sure it is
accounted for.