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2026-10-29

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How to set up a Fractional CFO agent in Gemini (Gems and skills)

If your business already runs on Google, Gemini is a natural home for a fractional CFO agent. The catch is timing: Google is replacing Gems with skills, and on personal Google accounts that switch starts in a few weeks. This guide shows both ways to load a full agent prompt, which one to pick for your account type, and how to test it. It uses Google's Gemini Apps help pages as checked on October 29, 2026.

It follows Vibewright's Fractional CFO · Entity Structuring builds (LLC vs S-corp vs C-corp, owner pay, entity upkeep), which are live now in five tones. The same steps work for any Vibewright build, including the free CFO · Tax Planner · Funny sample.

First: Gem or skill? It depends on your account

Google's dates for the move from Gems to skills (Google help: About the transition from Gems to skills):

Google says it will recreate existing Gems as skills automatically, along with supported files. Skills are available without a Google AI subscription and can be used in your chats. (Google help: Create & manage skills)

What you'll need

• A Google account signed in to Gemini at gemini.google.com. For skills, Google requires you to be 18 or over and to have Keep Activity on.
• A Vibewright build file (a Markdown system prompt): the free sample from /free, or a paid build from /pricing. Each CFO · Entity Structuring build runs about 22,000 to 23,000 characters.
• Optional: redacted notes on your current structure, state, owners and last year's net profit.

Option A: set it up as a skill (personal accounts)

1. Go to gemini.google.com (or the Gemini app on Mac).
2. In the sidebar, click Customize, then Skills at the top. If you don't see Customize, click More first.
3. Click Create, then Create manually.
4. Enter a name. Google requires all lowercase with hyphens and recommends starting with a verb, for example plan-business-entity-structure.
5. Enter a description. Gemini reads only the name and description to decide whether a skill fits your request, so say what it does and when to use it, in the third person, within 1,024 characters. For example:

   Acts as a fractional CFO for entity structuring: compares sole prop, LLC, S-corp and C-corp, models S-corp savings and owner pay, and tracks entity upkeep. Use when choosing or changing a business structure, setting an owner salary, or preparing entity questions for a CPA or attorney.

6. Paste the build into Instructions: everything below the line under the setup notes, from Absolute refusals (read first) to the end.
7. Click Create at the top.

Google's own tips say to keep skills short, "cheat sheets, not manuals," and its help pages don't publish a length limit for the instructions field. A Vibewright build is deliberately a full operating manual. If the field won't take the whole build, use the file route below.

File route. Paste only the four core sections (Absolute refusals, 1. Identity, 5. Communication style and 12. Guardrails, about 6,400 to 7,000 characters across the five Entity Structuring tones) plus a line telling the skill to read the full build file. Then follow Google's steps to add files: on the Skills page, click More options next to the skill and Download; put the SKILL.md from that .zip in a folder named exactly like the skill, together with your build's .md file; then click More options, Replace skill, and upload the folder. Skills accept .md files, up to 100 MB in total. (Google help) Google notes that Gemini opens skill files only when it needs them, which is why the refusals, identity, tone and guardrails belong in the instructions themselves.

Using the skill. In any chat, type / (or @ if you have the updated shortcut) and pick the skill. Gemini can also apply active skills on its own when they're relevant, and you can combine skills in one chat. To stop automatic use, open the skill on the Skills page and click More, then Deactivate. For now, skills don't work with Canvas or Deep Research. (Google help)

Option B: set it up as a Gem (Workspace accounts, or before Nov 17)

1. Go to gemini.google.com and click Open sidebar, then Gems. If you've never made a Gem, click Settings and help, then Gems.
2. Click New Gem.
3. Enter a name, such as CFO · Entity Structuring, and paste the build into the instructions.
4. Optional: under Knowledge, click Add files to upload the build file itself, or add a redacted entity summary from Google Drive. Drive files stay current: if you edit the file, the Gem uses the newest version. Adding from Drive needs Keep Activity on and Google Workspace connected to Gemini.
5. Click Save. A Gem made on the web also shows up in the Gemini mobile app and the Gemini side panel in Google Workspace.

To use it, open the sidebar, click Gems, and pick it under My Gems. Gems can't be used with Gemini Live for now. (Google help: Use Gems in Gemini Apps) On a personal account, a Gem you build today becomes read only on Nov 17, 2026, so build a skill instead unless you just want a quick trial.

Test it

1. Start a chat with the skill (/ and its name) or the Gem, and say "run onboarding", as the build's setup notes direct. The Entity Structuring builds open by asking for your structure and state, owners, last year's and this year's net profit, plans to hire, borrow or raise money, and whether you have a CPA and attorney.
2. Test the tone: ask a real question, such as whether your LLC should elect S-corp at your profit level, and check the voice matches the build you loaded.
3. Test the workflow: ask for the "S-corp election analysis." It should model low, mid and high reasonable salaries, subtract added costs, show a break-even profit level and produce a CPA handoff packet. (For the math behind it, see Should your LLC elect S-corp?)
4. Test the guardrails: ask it to help you keep deposits under a 1099 reporting threshold. It should open with a clear no, explain the risk and offer a legitimate alternative.

Keep SSNs, full EINs and full account numbers out of instructions, files and chats. Use redacted summaries.

Which Entity Structuring tone to load

Same comparisons and deadlines, five ways to hear them. All five are live now:

Not sure which one fits? See the five tones compared. Prefer another tool? Follow the setup guides for Claude Projects or ChatGPT Projects, or compare all three in Claude Project vs ChatGPT Project vs Gemini Gem.

The agent gives educational information, not tax, legal or accounting advice. Elections and formation documents go to your CPA and attorney.

Get the build

• Free sample: claim the CFO · Tax Planner · Funny build with your email and try these steps on a Vibewright CFO first. The download link lands in your inbox right away. License: Personal and commercial use allowed. No redistribution.
• Pick your tone: single build $9, role pack $49 (every Fractional CFO build), launch bundle $79, All-Access $19/mo or $149/yr, or Founding Member $199 lifetime for the first 100. 7-day refund on subscriptions. No refunds on downloads.

Choose your Entity Structuring tone on /pricing · Or grab the free Tax Planner sample