How to link/separate tags in a category

Hi
We have categories set up in this fashion.
Category:
1
1a
1b
1c

2
2a
2b
2c
These are NOT parent and child

We have about 15 tags we use to separate various entry types.
t1
t2
t3
t4

we would like to put links on a page that would only link to a tag in 1 category at a time.
Possible?
ty