An ACK or Acknowledgement is a term that is used a lot by both preparers and the technical team for UltimateTax. An acknowledgement is the term used to describe the message the IRS sent back to you (the tax preparer) indicating that they have received the return, and it has been either accepted or rejected.
You receive an acknowledgement anytime a federal or state return is accepted or rejected. You may view all of your currently received acknowledgements by going to Reports at the top of the program window, then select Acknowledgements. This function will list all acceptances, rejections, and IRS e-mails to keep you updated on various bits of information.
When viewing acknowledgements, they may appear like below, with information about multiple taxpayers, and the results of both state and federal returns.