We strongly encourage you to transmit your e-files at least two hours before the midnight (midnight Eastern time) deadline.
As the April 18th deadline approaches, the processing volume at the IRS will increase daily. Both return volume and return size will affect processing time. While you are accustomed to receiving your Federal acknowledgements within a one hour time-frame, that turnaround time will increase as the deadline approaches. You may see your acknowledgements take from 2 to 4 hours, and possibly longer.
This is why we suggest that you send returns periodically throughout the day. This will help spread out the volume and also help eliminate some of the 'deadline rush' which also impacts IRS processing.
Refer to this IRS.gov article for details on the April 18th deadline date
"People have until Tuesday, April 18, 2017 to file their 2016 returns and pay any taxes due. The deadline is later this year due to several factors. The usual April 15 deadline falls on Saturday this year, which would normally give taxpayers until at least the following Monday. However, Emancipation Day, a D.C. holiday, is observed on Monday, April 17, giving taxpayers nationwide an additional day to file. By law, D.C. holidays impact tax deadlines for everyone in the same way federal holidays do. Taxpayers requesting an extension will have until Monday, Oct. 16, 2017 to file"
