Forbes, When the IRS Says ‘Mail It In’, by Ashlea Ebeling:

Congress has instructed the IRS to get 80% of all individual taxpayers filing their 1040s electronically by 2012. But at the same time, it keeps creating special credits and provisions that mean some taxpayers still can’t file electronically–or at least can’t do so without sending supplementary documents and forms by snail mail.

In fact, there are so many situations where you must mail in certain documents within three days of e-filing, that there’s even a special form–8453–for mailing in paper documents after the e-filing fact. (The IRS conveniently counts taxpayers who mail in Form 8453 as electronic-filers. If it didn’t it wouldn’t have gotten to the 66% e-filing rate it bragged about last year.)

Exhibit A in this back-to-the-paper-future mess is the $8,000 first-time home buyer tax credit. When Congress extended and expanded the credit last November, adding a $6,500 credit for long-time homeowners who buy a new house, it decided taxpayers claiming the credit for 2009 or 2010 should file on paper. That’s because they must mail a copy of Form HUD-1, Settlement Statement, or another settlement statement, showing all parties’ names, the property address, the sales price and the date of purchase. …

So is there any hope to eliminate the paper? Perhaps. The IRS says that by 2012 e-filers should be able to finally send in supporting documents as attachments in Adobe’s PDF format.