You can jump during the "Pending Decommission" state; once it ticks over to "Decommissioned" you lose all access to carrier functions. Also remember you can decommission from anywhere, you don't have to be in carrier admin (although you do to remove any optional services).
Already done. Sold the services, then jumped it back to my home system to a planet farther out so it can sit till it disappears. Before the jump out, the screen said I was due 4.98 billion credits after decommissioning. That due to the 2000 tons of tritium I have stored on it, and the 927 tons in the tank that it probably calculated at the galactic average. I’ll be selling that myself and transferring a full T9 load to my new carrier,
You can buy a new carrier as soon as the maintenance downtime is complete and your old carrier has entered the Decommissioned state. Fingers crossed the discount lasts until that time... there's no absolute clarity about how long "a week" is. Common sense would say it ends on the Friday, but common sense would also lead you to believe the carrier Codex entry is mainly correct. (it is not)
Was trying to find you guys who wrote that report to ask that question. There was some good testing done, there were just a few extra details left out that impacted decisions here. Good to know that everything appears fine so far for the rebuy. If I get the discount, that’s great, if it expires because of a strange timer by FDev, oh well, I can certainly afford the 150 million and change loss for the sake of the experiment.
For the people at the start of this conversation, remember, this is why we ask these questions. Always do the research yourself, and try to find the original sources for your information. Just listening to a group of random blinky pixels on a computer screen and then taking what they say as truth will almost always fail you in the end. These forums help us all understand how the game works, and hopefully that translates into being a source of help for others, but only if we take the time to sort the wheat from the chaff, and are cognizant that we don’t propagate the false information. FDev is just as guilty of this with their Codex and others are.