What do I do if I am given an Article 15 that reduces me from SSG to SGT, but I PCS before it is processed?

SGT Michael Mason, I read through the different comments you had throughout the post and addressed them below rather than piecemeal.
---------------------------
I'm with MSG (Join to see), SGM Bill Frazer, and SGM Erik Marquez - someone screwed up.

You'll have an "adverse action" flag placed on your file when an Article 15 or UCMJ is initiated. That flag is non-transferrable and will stop you from PCSing.

When the Article 15 proceedings are completed and you have your punishment, you will have a "punishment phase" flag placed on your file for the duration of your punishment. These flags are transferrable and will allow you to PCS.

HOWEVER, if the punishment includes things that are "geographically limiting" such as extra duty, confinement, or restriction, then the original "adverse action" flag remains in place until the geographically limiting punishments are completed.

What SHOULD have happened is that you would have stayed at your old location until the extra duty was completed, the flag would be changed to a punishment flag for the rest of your punishment (the suspension of "2 months of a half-months’ pay" could be up to 6 months) and you would have been allowed to PCS at that point (assuming HRC still allowed you to go as you would go to an E-5 position, not an E-6 position).

Now, as to what is going to happen with you now.

I saw a few comments about who can and can't impose punishment, so I want to give you the straight answer.

The "imposing commander" is the one that imposes the punishment from your article 15 (this is your old commander who gave you the reduction, extra duty and suspended forfeiture of pay). However, any commander who has the appropriate authority over you, may impose punishment on you.

Normally the imposing commander must be the same throughout the process from the time it is initiated until the punishment is complete. The exception is when you cease to be under that commander's authority because one of you changes units. Per AR 27-10*, para 3-8b:

"Termination of status. Once a member ceases to be part of the command as outlined in paragraph 3–8a, the authority of the losing commander to impose NJP over that member terminates. However, if UCMJ, Art. 15 proceedings have been initiated and punishment has not been imposed prior to the time of the change of the member’s assignment, the commander who instituted the proceedings may transmit the record of proceedings to the gaining commander for appropriate disposition. This only applies when the member changes command. Proceedings initiated prior to a change in the individual exercising command, whether temporary (under an acting commander) or permanent (change of command), the punishment may be imposed by a lawful successor-in-command."

The DA 2627, which lists all the punishments given as well as which were executed or suspended, will be forwarded to your new unit. Your new commander will see that the 2 months of half-pay was suspended but that the reduction in rank and extra duty was executed.

While para 3-8b above may make it sound like the reduction won't happen at your old unit, it will. The punishment was executed (imposed) by your old commander prior to your PCS. At that point (not when the administrative records are updated), you were no longer a SSG, you became a SGT again. The records may be wrong because the paperwork hasn't gone through the process yet, but when the packet finishes its local processing, HRC will be notified, a reduction order will be issues/placed in your AMHRR, and IPPS-A will be updated.

Regarding extra duty - that will be completely up to the discretion of your new field grade authority (battalion commander assuming you're in a line unit) and how much your old unit pushes for the remainder of it to be implemented. The old commander could send an amplifying letter explaining the circumstances why you were allowed to PCS while still under extra duty and request that the new command implement it the remainder ... or the old commander might not care about it at all. Bottom line - your new commander will implement it, if they are so inclined (personal note - If I was the new commander, I'd likely not do it and just suspend the punishment to match the timeline of the pay suspension so you could start at a new unit on the right footing).

As for the suspended pay. If you screw-up within the timeframe of the suspension, and your new FG authority wants to, they can implement whatever punishment was suspended immediately. Don't screw up.

While it is strange that your packet "hasn't made it back from legal nor to S1", the fact that you PCSed before it was processed is immaterial. The legal review is 99% likely to have nothing to do with you (you would have been given 5 days ask for reconsideration or appeal to higher your punishment). It probably is anything from making sure the “I”s are dotted to making sure the correct additional notifications are completed according to local/installation policy.
-----------------------------------
* DA Form 2627 - https://armypubs.army.mil/pub/eforms/DR_a/pdf/A2627_2.pdf
* AR 27-10 (Military Justice) - https://armypubs.army.mil/epubs/DR_pubs/DR_a/ARN31271-AR_27-10-001-WEB-2.pdf
* AR 600-8-19 (Enlisted Promotions and Demotions) - https://armypubs.army.mil/epubs/DR_pubs/DR_a/ARN36067-AR_600-8-19-000-WEB-1.pdf

I suspect that you will not be PCSing during the UCMJ process -- this isn't a pass on to the next commander situation. Since you imply you will be reduced and there is no hint of innocence here - expect to carry on as a SGT immediately after the proceedings happen; expect to be stripped of the rank while in the room and S1 will process paperwork soon after. I would also recommend that you start soldiering right and get your resume in order, because your future in the service may be short-lived

1. Any Judicial actions immediately stop all personnel actions until they are resolved. Then personnel actions can resume. With a reduction in rank, HRC will have to decide if there remains a slot for you to PCS into.