I am mailing my federal and California state tax returns. Can I print double-sided?

[MicheleR]

You can, however, it is suggested that you print per page. 

If you print double-sided you would want to make sure it is the same form, for example, page one of the 1040 and page two on the back. 

Keep in mind by using only one-page per-form will reduce clerical errors. Also, you want to make sure you are printing only the forms required for filing, this should not use up that much paper.