It IS necessary to qualify for the extension to attach a statement, and ProSeries is the only program that doesn't seem to do this automatically.  Heck, even TurboTax can do it.   By October you might think 4868 has been filed but many a client has walked in my door late in the year to start the process and it matters that you make the note that they qualify for the 6/15 filing date.  Their address is meaningless for this, as many may live abroad but use a US address for mail or lived abroad on 6/15 of the prior year but no longer do.