On Mar 17, 10:10*am, wrote:
In a bedroom, I need to build a new interior partition 90 degrees off
an existing wall. *The existing wall is painted (Benj. Moore eggshell
latex) and the new construction will need to be taped at the corner
where they join together. *Can I just tape this corner like it was all
unfinished drywall, or will I need to prep the existing painted
surface to affect a good bond and sound tape joint?

If you choose to use a conventional right angle joint, it only takes a
couple of minutes to scarf off the area where the taping takes place.
Most people would just use an angle grinder with whatever abrasive
disc is handy. Keep your shop vac handy and the small amount of dust
won't be a problem. HTH

Joe