The dates in this article fall in the next few weeks, and AI vendors change features almost weekly. Check the published date on this page and confirm each date in your own account. For training and materials that match today's tools, contact Softwired.
The short answer
A custom assistant is a reusable set of instructions and reference files for a job you do often. ChatGPT calls these custom GPTs and Gemini calls them Gems. Both are moving to skills: packaged instructions, examples and files that the AI applies when a task matches, and that you can combine. In ChatGPT, skills sit inside plugins, which can also bundle connected apps.
Custom GPTs are scheduled to retire on 11 December 2026. Gems become read-only for personal Google accounts on 17 November 2026, and Google removes them on 17 December 2026.
Most of the work you put into a GPT or Gem moves across. The sections below show what transfers and what you'll need to redo before each deadline.
Why custom assistants are becoming skills
A custom GPT or Gem was a separate assistant you switched to for one job. A skill teaches the AI how you like that job done, and the AI uses it in any chat. Google says Gemini skills work in your current chat, apply automatically when relevant, and stack together. Anthropic describes Claude's skills the same way: you show Claude how you like a task done, and it follows those steps whenever the task comes up.
What each tool calls it
| Tool | Old name | Current name | Key facts (checked 31 October 2026) |
|---|---|---|---|
| ChatGPT | Custom GPTs | Plugins (containing skills, apps or both) | Custom GPTs are scheduled to retire on 11 December 2026. FedRAMP workspaces and workspaces with an approved deferral have until 11 February 2027. Personal accounts (Free, Go, Plus and Pro) can no longer create new GPTs. To move a GPT, use "Migrate to plugin" in My GPTs; the GPT must be published. Skills are available to eligible Business, Enterprise, Healthcare and Edu users. |
| Gemini | Gems | Skills | Personal accounts (18+): Gems are read-only from 17 November 2026 and removed on 17 December 2026. Workspace business accounts follow in March 2027, and education accounts in June 2027. Google converts Gems to skills automatically. |
| Claude | Not applicable | Skills and plugins | Skills teach Claude repeatable ways of working. Plugins bundle skills and connectors. Claude supports the open Agent Skills standard. Find both under Customize. |
| Microsoft 365 Copilot | Agents | Agents, plus custom skills in PowerPoint | Microsoft lets you build agents in Copilot Chat or Copilot Studio. Custom skills are now available in PowerPoint. |
| Grok | Not confirmed | Not confirmed | No equivalent is described on official pages. |
| Meta AI | Not confirmed | Not confirmed | No equivalent is described on official pages. |
What a skill contains
Most skills share a simple shape: a folder with a file called SKILL.md, holding
- a name and a description that tell the AI when to use the skill
- instructions, the steps or rules to follow
- examples of good output
- optional reference files, and in some tools, scripts.
Claude's skills use this format. Google says you can import skills built on other platforms into Gemini by uploading their SKILL.md files. ChatGPT also lets you upload a skill from your computer.
How you'd actually use it
Build a proposal-writing skill
Name it "proposal-writer". Give it the description "Use when drafting a client proposal or quote cover letter." Add your structure, tone and must-include terms as the instructions, and two of your best past proposals as examples. From then on, a request like "Draft a proposal for a three-day site audit for a Gold Coast client" picks up the skill in any chat, and you stop pasting the same brief every time.
Stack two skills in one chat
In Gemini, combine a "meeting-agenda" skill with an "Australian English style" skill, and the agenda comes back in your house spelling.
Migrate a custom GPT
In ChatGPT, go to My GPTs and choose Migrate to plugin. Test the new plugin on a few familiar prompts and one harder case before you share it.
What carries over when you migrate
ChatGPT: custom GPT to plugin
OpenAI lists what moves across and what you'll need to redo:
- Your instructions become a skill, your knowledge files are copied across, and connected apps come across as apps.
- Custom actions stay behind. Someone will need to rebuild them, possibly as an MCP connection (see AI connectors, apps and MCP explained).
- The GPT's selected model and its conversation starters stay behind too.
- The new plugin starts private, so share it again with the people who need it.
- Once you migrate, the original GPT is read-only until it retires.
- Migrated plugins work in Chat and in Work, ChatGPT's agent mode (see What is an AI agent?), wherever plugins are enabled.
Gemini: Gem to skill
- Skills have a 100 MB file limit. Google drops the largest files first from Gems over that size.
- Audio, video, archives (.zip and similar), GitHub files and legacy Office formats (.doc, .xls, .ppt) stay behind.
- Skills currently can't be used with Canvas, Deep Research, video or music creation, or Guided Learning.
- Download any files you need before 17 December 2026.
Watch-outs before the deadlines
- Test each migrated assistant before its deadline. It may answer differently, because the model and conversation starters change.
- If you use a GPT or Gem someone else built, ask the creator what will replace it.
- On work accounts, admins may decide who can create or publish plugins and skills.
Frequently asked questions
Will my Gems disappear?
For personal Google accounts, Gems become read-only on 17 November 2026 and are removed on 17 December 2026. Google converts them to skills automatically, though some file types won't transfer.
Do I need to migrate my custom GPT myself?
Yes. If you created the GPT, use Migrate to plugin once it appears in your account, then test the result.
Is a skill the same as a project?
They do different jobs. A project holds the background for one ongoing piece of work. A skill holds the know-how for a type of task, and you can use it in any chat.
Related guides
- What is a project in ChatGPT, Claude and other AI tools?
- What is an AI agent? Cowork, Work and Task explained
- AI tool features explained: a plain-English guide for 2026
Put it to work with AI On Ramp
If your team relies on custom GPTs or Gems, the deadlines make now the time to rebuild them as skills people use every week.
AI On Ramp gets your team using AI with confidence, on their own work and across teams, while you keep its cost and risk under control. We set up the tools, then our consultants sit beside your most advanced AI users and build real in-house workflows with them. Your nominated AI Lead gets the governance tools and our ongoing support to keep the business current as the tools change. We bring deep technical expertise and decades of business change management, and we work face to face from Brisbane and along Australia's east coast. See how AI On Ramp works.
Want to talk through how this applies to your team? Book a call with Softwired.
