org-tags-column controls the distance of tags at the end of the heading. To have just one space, the original poster may wish to consider using:
(setq org-tags-column 0)
To apply the changes on an existing org file, use
C-u C-c C-q
The doc-string for
org-tags-column, which can be seen by typing
M-x describe-variable RET org-tags-column RET states as follows:
"The column to which tags should be indented in a headline. If this number is positive, it specifies the column. If it is negative, it means that the tags should be flushright to that column. For example, -80 works well for a normal 80 character screen. When 0, place tags directly after headline text, with only one space in between."