Apparently the US tax people are expecting people to do this.
The commonest one, xpdf, is explicitly a viewer only and qpdfview only allows rotation and scaling. According to Wikipedia the only programs that explicitly allow you to edit an existing PDF file and run under Linux are: LibreOffice Draw, OpenOffice Draw, PDFedit, Pdftk, PDF Studio and Karbon
Of this lot, I've only heard of the first two until now and others have said that Pdftk is just a set of command line tools, nor with a GUI front end and are a faff to use.
So what do you use to edit PDF files?
Bob Prohaska: were you just trying to use LibreOffice Writer or did you try LibreOffice Draw too?