sorry, this happens in a text-mode buffer with whitespace-mode on. without whitespace mode it only occupies one column.

2014-09-10 1:55 GMT-05:00 Mario Valencia <mariovalspi@gmail.com>:

In a buffer, set tab-width to 6. then insert 5 characters, then a literal tab character (C-q TAB). Now you have a 7 column tab.