When the P11D Organiser submits the end of year information to HMRC, it collates all of the relevant information into a single XML file (that contains both employer P11D(b) AND employee's P11D data) into a single XML file that is then sent to HMRC via the Government Gateway over a secure connection (based on your Government Gateway credentials).

If you ever need to check the information that was sent, the XML file remains available for you to review - it is not the most readable of formats, but can be helpful when discussing submissions with HMRC.

If you navigate to HMRC Filing > EOY File By Internet - FBI within the software, you will see a confirmation of your submission:

There are a number of areas/button that can assist with any investigative work:

1 - ConfirmationsThis show the date/time that contact was made to HMRC, the unique correlation ID, and the date/time that your submission was accepted by HMRC. Please note that HMRC servers always run based on GMT, so the times you see here may appear an hour different to what you expect.
2 - LogThis is an overview of what was sent and includes the total Class 1A, the amount owing and details about the number of P11Ds and sections submitted
3 - ModifiedThis button will build a list of all the employee records that have been changed within the system since the FBI was performed - this is useful for amendments.
4 - View XMLThis button displays the actual XML file that was sent to HMRC. It can be challenging to read (although you can view this is a number of different applications), but you can search by NI number to see exactly what was sent to HMRC.
5 - PrintThis will show the 'receipt' of transmission as a PDF file - this has a range of information that may be useful.
6 - EmailThis button allows you to email the receipt and XML to an address of your choosing.
7 - ListThis performs a lookup of all the employees that were included in the submission.