If your team built custom GPTs, this is the issue to read. OpenAI is replacing them with plugins, and the standard retirement date is 11 December 2026.
There is more: a Word add-in that is already switched on, a shared usage allowance arriving in December, and free API credits that nobody will claim unless you do. OpenAI’s help pages block automated reading, so we checked these against archived copies of OpenAI’s own pages from late October and early November. Prices are in US dollars.
Entries are numbered so the checklist can point to them.
If you only have 2 minutes
- 1Custom GPTs stop on 11 December. Whoever built each one needs to migrate it to a plugin, test it and share it again.
- 2ChatGPT for Word is already on. On by default since 1 October, and it uses your paid allowance.
- 3One allowance from December. ChatGPT and Codex start sharing usage, so heavy users will hit limits sooner.
- 4Free API credits to claim. Business workspaces earn monthly API credits, capped at US$500 a month.
- 5GPT-5.5 is gone. Retired from ChatGPT on 14 October. Check anything that named it.
Checklist
Do first
- List every custom GPT, who built it and who uses it · Now · see 1
- Migrate, test and re-share the GPTs you need · Before 11 December · see 1
- Decide whether you want ChatGPT for Word on · Now · see 4
- Check defaults, agents and scheduled tasks that named GPT-5.5 · Now · see 3
- Have the workspace owner claim the API credits · This month · see 5
When you have time
Deadlines
1.Custom GPTs retire and become plugins
Who: Business and Enterprise · Rollout: Standard retirement 11 December 2026 · Where: My GPTs
Custom GPTs are being replaced by plugins. The person who built a GPT migrates it from My GPTs using “Migrate to plugin”. The original becomes read-only, and the new plugin starts out private.
Custom actions, model choice and sharing settings do not carry across. Actions may need rebuilding as an app or a custom MCP server. Some Enterprise workspaces have different dates; check your workspace notice.
Why this matters
Anything your team does through a custom GPT stops working on 11 December unless it has been migrated, tested and shared again. GPTs that call your systems through custom actions need the most work.
- In plain words: Custom GPTs are ending. Each one needs moving to a plugin by its creator, before 11 December.
- A real-world example: A freight forwarder has a GPT that looks up shipment status through a custom action. Migrating copies the instructions, but not the connection to its system, which has to be rebuilt.
- Our take: Treat this as a small project, not a click. Start with the GPTs that use custom actions, because those are the ones that need building again. If you need a connector rebuilt, that is exactly what we do.
Custom GPT
Shipment lookup
becomes read-only
Plugin
Shipment lookup
starts private
- Name and instructions✓ carries over
- Knowledge files✓ carries over
- Custom actions✕ rebuild or reset
- Model choice✕ rebuild or reset
- Sharing settings✕ rebuild or reset
OpenAI Help Center: Custom GPT retirement and migration FAQ · OpenAI Help Center: ChatGPT Business release notes
2.ChatGPT and Codex share one allowance from December
Who: Business users · Rollout: From December 2026 · Where: Settings → Usage
Usage will be counted in tokens and shared across ChatGPT and Codex. Bigger models and complex tasks use the allowance faster. Remaining usage and reset times will show in Settings → Usage.
Why this matters
People who lean on Codex or long tasks could run short for everyday work, usually at the worst moment.
- In plain words: One shared allowance, and heavy jobs use more of it.
- A real-world example: A developer uses Codex heavily all morning, then finds ChatGPT limited when they need to write up a client report in the afternoon.
- Our take: Tell your heaviest users now, and check Settings → Usage once December starts before buying more.
One allowance, shared
Bigger models and long tasks use it faster.
OpenAI Help Center: Understanding ChatGPT and Codex usage limits
3.GPT-5.5 retired from ChatGPT
Who: Everyone on paid plans · Rollout: Retired 14 October 2026 · Where: ChatGPT, Work and Codex
GPT-5.5 can no longer be picked in ChatGPT, Work or Codex on any plan. The API is not affected.
Why this matters
Saved defaults, agents and scheduled tasks that named it may now behave differently.
- In plain words: One model has gone; anything set to use it has changed.
- A real-world example: A weekly scheduled summary that was set to GPT-5.5 now runs on a different model, and reads differently.
- Our take: A five-minute check of anything automated. Worth doing.
Cost and usage
4.ChatGPT for Word is on by default
Who: Admins, and Microsoft 365 admins · Rollout: Launched 17 September; on by default from 1 October · Where: Microsoft Word
People can draft, summarise and revise inside Word with the ChatGPT add-in. Use is charged at API rates against your premium allowance. Workspace admins can switch it off, and Microsoft 365 admins must also allow the add-in.
Why this matters
It is already on unless someone turned it off, and it spends the same allowance as everything else. If you also pay for Copilot, two assistants may now be offering to help in Word.
- In plain words: ChatGPT can now work inside Word, and it is switched on.
- A real-world example: A law firm on Microsoft 365 with Copilot discovers staff using both assistants in the same documents, under two different sets of rules.
- Our take: Make a decision rather than inherit one. If Copilot is your Word assistant, switch this off.
5.Monthly API credits for Business workspaces
Who: Business workspace owners · Rollout: Rolling out from 28 October 2026 · Where: Billing
Paid seats earn API credits, pooled across the workspace and capped at US$500 a month. Only someone who owns both the ChatGPT workspace and the API organisation can claim them. They expire each billing cycle and do not raise ChatGPT limits.
Why this matters
Free budget for testing connectors and automations, lost every month nobody claims it.
- In plain words: Free API budget, if the owner claims it.
- A real-world example: A 20-person business uses its credits to prototype an agent that drafts replies from its order system, before spending anything.
- Our take: Claim them, and use them to test something real.
OpenAI Help Center: API credits benefit for eligible ChatGPT subscriptions · OpenAI Help Center: ChatGPT Business release notes
For admins
7.New admin controls, mostly off by default
Who: Business admins · Rollout: August to October 2026 · Where: Admin console
New options include Computer History on macOS, letting Sites use members’ connected apps, @ChatGPT in Slack and Teams, team tasks, and bulk management of plugins in the Admin Console. Most need an admin to switch them on.
Since 20 October, people can lock chats behind a PIN. Locked chats do not change your workspace policies or retention settings.
Why this matters
Each of these widens what ChatGPT can reach. None of them should be switched on by accident.
- In plain words: More settings to decide on, and most are off until you say yes.
- A real-world example: A business that runs on Slack switches on @ChatGPT for one channel to try it, and leaves the rest off.
- Our take: Go through them once, decide yes or no on each, and write down why. Next time someone asks, the answer is already there.
Watching next month
- Any change to the 11 December retirement date
- How large the shared ChatGPT and Codex allowance turns out to be
- Plugins once migrated GPTs are in use
How this issue was put together
OpenAI’s help pages block automated reading, so we checked each fact against archived copies of OpenAI’s own pages from late October and early November, and left out anything only reported second-hand.
Every fact links to its source. Prices are in US dollars. The examples are made-up New Zealand businesses, not clients. The figures are our own illustrations, not OpenAI screenshots.