# Budget against actual, in plain words

**A Neosaipien skill for AI assistants. Version 1.1, as of 16 October 2026.**
Free, under the Neosaipien free licence, Version 2.

## What it does

You give your assistant a spreadsheet export (a CSV file) or paste a table of budget and actual figures. The skill then:

- works out the difference and the percentage for every line, and shows the sum behind each one;
- marks the lines that are over the threshold you set (for example "more than 10% and more than 2,000, either way");
- lists data problems it finds, such as blank cells, entries that look ten times too big, negative costs, duplicated rows and totals that do not add up, without quietly fixing any of them;
- writes a 150 to 250 word draft summary for a manager or a board, using only the reasons you give it. Anything you have not explained is marked "Cause to confirm".

If your assistant can run code, it does the sums with code. If it cannot, it writes out each sum so you can redo it.

## Who it is for

Managers who hold a budget, operations and finance staff, and small business owners writing a monthly or quarterly update.

## What is inside

| Item | What it is |
|---|---|
| `budget-vs-actual.zip` | The skill, ready to upload to Claude |
| `portable/budget-vs-actual-for-gemini.zip` | The same skill, packed with `SKILL.md` in its main folder, for Gemini |
| `skill/budget-vs-actual/` | The same skill as a folder: `SKILL.md`, `LICENSE.txt` and four reference files. `SKILL.md` is the file for ChatGPT |
| `references/method.md` (inside the skill) | How it treats refunds, credits, one-off items, blanks and odd entries |
| `references/threshold-guide.md` (inside the skill) | How to set and word a threshold, with two starting points |
| `references/board-summary-format.md` (inside the skill) | The summary format. Edit it to your own house style |
| `references/worked-example.md` (inside the skill) | A small example with its full answer |
| `portable/paste-in.txt` | A plain-text copy for a plan without skills: paste it into a project's instructions, or at the start of a chat |

If a tool takes only `SKILL.md`, the skill still works: it says once that its reference files are missing and follows the rules written into its own steps.

## Add it to your AI tool (as of Oct 2026)

All three tools now take skills in the same open format, a SKILL.md file. The format began at Anthropic and is now an open standard. So this is one skill, not a version per tool. Use the tool your company approves for work data.

If you cannot see a menu below, the usual reasons are a rollout still in progress, your plan, your country or an admin setting.

### Claude

**Plans:** Pro, Max, Team and Enterprise, says Anthropic's skills page (its pricing table also ticks Free).

1. In **Settings > Capabilities**, turn on **Code execution and file creation**. Skills need it.
2. Go to **Customize > Skills**.
3. Upload `budget-vs-actual.zip`. It holds the SKILL.md file and its reference files.
4. To use it, describe the task in a chat, or type **/** and pick **budget-vs-actual**.

Anthropic does not review skills made by other people, so read a skill's files before you turn it on. This one is plain text: open `skill/budget-vs-actual/SKILL.md` to read it. A skill you add in Claude also follows you into Claude Code when you sign in with the same account.

### ChatGPT

**Plans:** skills are a beta on Free and Plus, and generally available on Enterprise and Edu (since 9 Jul 2026). ChatGPT keeps skills inside plugins, in the Plugin Directory.

1. Start a new chat and type **@skill-creator**.
2. Attach `skill/budget-vs-actual/SKILL.md` and the files in `skill/budget-vs-actual/references/`, and write: "Make a skill from these files. Keep its name, description, instructions and reference files exactly as written."
3. Check that the skill it shows you matches the files.
4. To use it, describe the task, or type **@** and pick **budget-vs-actual**.

### Gemini

**Plans:** 18 or over, with a personal Google Account. Google says work and school accounts get skills "soon".

1. Open the left menu, click **Customize**, then **Skills**.
2. Make a new skill by uploading a SKILL.md: choose `portable/budget-vs-actual-for-gemini.zip`, which has the SKILL.md in its main folder with the reference files beside it. If your screen takes only a single file, choose `skill/budget-vs-actual/SKILL.md`; it works on its own.
3. To use it, describe the task, or type **/** (Google says **@** is coming) and pick **budget-vs-actual**.

Gemini wants skill names in lowercase with hyphens, which this one has, and allows up to 100 active skills.

### No skills on your plan? Use a project

- **Claude or ChatGPT:** make a project for this job and paste the whole of `portable/paste-in.txt` into the project's instructions. Every chat in that project then follows it. In ChatGPT: select **New project** in the sidebar, name it, then add instructions from the **•••** menu under **Project settings**.
- **Gemini with a work account, or any single chat:** paste `portable/paste-in.txt` as your first message. It lasts for that one chat.

There is no custom GPT or Gem version: OpenAI plans to retire custom GPTs in favour of plugins, and Google is moving Gems to skills from Nov 2026 for personal accounts and in 2027 for work and school accounts.

**For your whole organisation.** Ask whoever runs your company's Claude, ChatGPT or Gemini account to add it for your staff. Each tool has its own admin settings.

## Which tool, mode and model to use

**My recommendation: Claude first, ChatGPT second, Gemini third.** (Samson, Neosaipien.) Spreadsheet work is where Claude is strongest today: it does the sums with code, and Claude for Excel cites cells and keeps formulas intact.

| | Claude | ChatGPT | Gemini |
|---|---|---|---|
| Where to run it | Any ordinary Claude conversation, with your CSV attached | Chat, with your CSV attached | Chat, with your CSV attached |
| Model for a short, clean export | Sonnet 5.5 at its Default effort | GPT-6 at Medium | Flash |
| Model for a long or messy export | Opus 5.5 | GPT-6 at High | Pro, thinking High |
| Working inside the spreadsheet afterwards | Claude for Excel (Pro and up): clickable cell references, formula-safe edits, a warning before it overwrites | The Excel and Google Sheets add-ins (limited on Free, full from Plus) | Gemini in Sheets (Workspace editions) |
| Worth setting up | A project holding your board-summary format and last month's report | A project holding the same | Nothing extra |

- **Where to pick the model:** Claude, the model name next to the send button. ChatGPT, GPT-6 in the model menu, then the Thinking slider. Gemini, the current model at the bottom of the chat box.
- **Plans:** Opus 5.5 needs Claude Pro or above. GPT-6 needs ChatGPT Plus or above; Free and Go use GPT-6 Luna. Gemini's Flash and Pro need a Google AI plan.
- **Repeat it every month:** in Claude you can schedule repeat work, such as a report every Monday. Keep the output a draft: the skill never sends anything.

## How to use it

Start a new chat, attach your CSV (or paste your table) and say what you need in one message. For example:

> Here is our cost export for July to September 2026. Budget against actual for the board pack, please. Flag anything more than 10% and more than 2,000 either way. What we know: one extra hire started in August, and our main software went up in price from July.

The reply comes in six parts: data problems, the line-by-line table, the draft summary, causes to confirm, the working, and what to check before you use it. If you leave something out, such as the threshold, it will ask you, at most three questions in one go.

## What you must check

The skill is careful and shows its working, but it is a draft, and it cannot see what is not in your file.

- Recompute the largest lines and the totals in your own spreadsheet.
- Check the export is complete (every line and every month) and covers the right period.
- Remove personal data, such as named salaries, before you upload a file, and follow your organisation's rules on what may be uploaded to an AI assistant.
- Confirm every "Cause to confirm" with the person who owns that line.
- Have a finance owner review the summary before it reaches a board.

## What it does not do

- It does not build budgets or forecasts, do bookkeeping, or give tax, accounting, audit, legal or investment advice.
- It does not guess reasons. A reason appears only if you gave it.
- It does not fix your data. Problems are listed for you to fix in the source.
- It does not send, post or share anything, and it does not use the internet.
- It does not promise that any output is correct, or that it saves time.

## Compatibility, as of October 2026

| Tool | Who can add skills (vendor's own pages) | Which file |
|---|---|---|
| Claude | Pro, Max, Team and Enterprise (the pricing table also ticks Free), with code execution on | `budget-vs-actual.zip` |
| ChatGPT | A beta on Free and Plus; generally available on Enterprise and Edu | `skill/budget-vs-actual/SKILL.md` and its reference files, through @skill-creator |
| Gemini | 18 or over, personal Google Accounts; work and school accounts "soon" | `portable/budget-vs-actual-for-gemini.zip`, or `skill/budget-vs-actual/SKILL.md` on its own |
| A plan without skills | Everyone, through a project's instructions or one chat | `portable/paste-in.txt` |

"Who can add skills" is what each vendor's own page says, as of October 2026. These tools change often.

- **Format:** the open Agent Skills format: one `SKILL.md` with a name and description, plain-text reference files, no scripts. Reference files are `.md` and `.txt` only.
- **Tested:** on 16 Oct 2026 a tester who had not seen the answers followed the instructions step by step on all three practice files, and every figure, flag, data problem and cause matched the expected answer. After small fixes, practice file 2 was run again the same way and matched. It has not yet been tested inside each tool listed above. Each tool updates its features often; check the steps against your own screen.

## Your data

The skill sends nothing anywhere and needs no internet. It works only with what you give it inside your assistant, and your assistant's own data terms apply.

## Licence and support

- Free, under the Neosaipien free licence, Version 2. Use it as much as you like, at work or at home, in any organisation. Change it to fit your team, and hand the changed version to people inside your own organisation, team, class or group, with the credit, the date and a line saying it was changed. Share unchanged copies with anyone, free of charge. Do not sell it, and do not publish a changed version outside your own group. Full terms in `skill/budget-vs-actual/LICENSE.txt`.
- Questions: samson@neosaipien.com
- Neosaipien is not affiliated with or endorsed by Anthropic, OpenAI or Google. Product names belong to their owners.

## Sources for the setup steps (all read 16 October 2026)

- Anthropic, Skills overview: https://claude.com/docs/skills/overview.md
- Anthropic, Claude plans and pricing: https://claude.com/pricing
- Anthropic, What are projects: https://support.claude.com/en/articles/9517075-what-are-projects
- Anthropic, Connectors, skills, and plugins: https://claude.com/docs/extend/overview
- Anthropic, Change the model, effort, and thinking settings: https://support.claude.com/en/articles/8664678-change-the-model-effort-and-thinking-settings
- OpenAI, Skills and plugins: https://learn.chatgpt.com/docs/skills-and-plugins.md
- OpenAI, Build skills: https://developers.openai.com/plugins/build/skills.md
- OpenAI, ChatGPT release notes: https://help.openai.com/en/articles/6825453-chatgpt-release-notes
- OpenAI, ChatGPT plans and pricing: https://chatgpt.com/pricing/
- OpenAI, Projects in ChatGPT: https://help.openai.com/en/articles/10169521-projects-in-chatgpt
- OpenAI, GPT-6 and other models in ChatGPT: https://help.openai.com/en/articles/20001354-gpt-6-and-other-models-in-chatgpt
- Google, Create and manage skills for Gemini Apps: https://support.google.com/gemini/answer/17094296
- Google, About the transition from Gems to skills: https://support.google.com/gemini/answer/18560919
- Google, About Gemini models: https://support.google.com/gemini/answer/18648722
- Agent Skills overview: https://agentskills.io/
- Anthropic, Use Claude for Excel: https://claude.com/docs/office-agents/excel.md