If you are living overseas, you have an automatic 2 month extension (to June 15). But to use this, you must file by mail, and attach a written explanation. Or, you can request an automatic 6 month extension which applies to everyone. That will give you until October 15, and you can e-file. You must apply for the extension before April 15. You can apply online, but the function is not turned on yet in Turbotax (usually turned on sometime in March). Or you can mail a paper application.
https://www.irs.gov/forms-pubs/extension-of-time-to-file-your-tax-return
