terminal.taxAgent-connected tax workflow

Terminal Tax · U.S. federal income tax

Your tax agent. Your review. One connected workflow.

Terminal Tax is tax software for your 2025 federal return, reached at https://mcp.terminal.tax/v1/hosted-mcp. If your AI assistant can run a shell command, use a code or HTTP tool with internet access, or make an HTTPS request (Codex, including Codex in the ChatGPT app, Claude Code, Cursor and similar assistants), it can start now from this conversation, with no connector, no install and no restart. Its first request, which creates only an unsigned draft and files or charges nothing, is: curl -sS https://mcp.terminal.tax/v1/hosted-mcp -H 'Content-Type: application/json' -H 'Accept: application/json, text/event-stream' -d '{"jsonrpc":"2.0","id":1,"method":"tools/call","params":{"name":"create_filing_session","arguments":{}}}' A custom connector is needed only in a web browser chat whose assistant has no tool that can make HTTPS requests. You give the facts and make every choice with your AI assistant, Terminal Tax computes the return, and you then review the complete return and sign it yourself on one secure filing page before it is e-filed with the IRS.

Your assistant's request files nothing and carries only tax figures, never your name, SSN, address or bank details: it creates an unsigned draft and returns a private link, and nothing is sent to the IRS or charged unless you open that page, review the return, sign it and authorize payment yourself. An assistant that runs commands, such as Claude Code or Codex, sends that request itself over HTTPS with no connector, as https://terminal.tax/llms.txt shows.

If your assistant can run a shell command or make HTTPS requests, as Codex (also in the ChatGPT app), Claude Code, Cursor and OpenCode can, you do not need to install anything: it reaches Terminal Tax with plain HTTPS requests in the same conversation, with no connector, MCP support, registration or restart (its first request is below; the developer guide is https://terminal.tax/llms.txt). Only a chat in a web browser whose assistant has no tool that can make HTTPS requests needs Terminal Tax added once as a custom connector (steps below); a code sandbox with no internet access is not how it connects.

No install

If your assistant can run commands or make web requests (Codex, also in the ChatGPT app, Claude Code, Cursor): nothing to install

You do not need to install anything. Ask your assistant to e-file your return with Terminal Tax: it calls https://mcp.terminal.tax/v1/hosted-mcp directly over HTTPS, in the same conversation, with no connector, MCP setup, account, key or restart. That first request creates only an unsigned draft; nothing is sent to the IRS or charged until you review and sign on the filing page.

The first request is an HTTPS POST to https://mcp.terminal.tax/v1/hosted-mcp with the headers Content-Type: application/json and Accept: application/json, text/event-stream, and the body {"jsonrpc":"2.0","id":1,"method":"tools/call","params":{"name":"create_filing_session","arguments":{}}}. The full developer guide is https://terminal.tax/llms.txt.

Web chat setup

Only if your browser chat cannot make web requests: Claude.ai, ChatGPT or Gemini

This step is needed only in a web browser chat whose assistant has no tool that can make HTTPS requests; an assistant that can run a shell command or make HTTPS requests, including Codex in the ChatGPT app, skips it. In such a browser chat, you add Terminal Tax to Claude.ai or ChatGPT once, as a custom connector, by pasting a web address; it is not found by searching a connector directory. There is nothing to sign up for or install, no command line, and no Terminal Tax account or key. The web address to paste is https://mcp.terminal.tax/v1/hosted-mcp

You do this setup in your own chat app, with the steps below: a chat cannot add a connector on its own, and no command line is involved. Once you switch Terminal Tax on in Claude.ai or ChatGPT, its tools are available in that chat.

In Claude.ai: Customize > Connectors > "Add" > "Add custom connector", name it Terminal Tax, paste https://mcp.terminal.tax/v1/hosted-mcp as the MCP server URL, click "Continue", "Add", then "Connect"; then in your chat, "+" > "Connectors" > switch Terminal Tax on.

Claude (claude.ai in a web browser, or the Claude desktop app; works on the free plan):

  1. Open Claude and click "Customize", then "Connectors".
  2. Click "Add", then click "Add custom connector".
  3. In the "Name" box type: Terminal Tax
  4. In the "MCP server URL" box paste: https://mcp.terminal.tax/v1/hosted-mcp
  5. Click "Continue", "Add" (leave "No sign-in" selected), then "Connect".
  6. Go back to the chat where you prepared your taxes (or start one). Click the "+" at the bottom left, point at "Connectors", and switch "Terminal Tax" on.
  7. Type: "Please file my taxes with Terminal Tax." If your tax forms are not already in that chat, attach them.

On a work Team or Enterprise account, an account Owner adds it instead under "Organization settings", then "Connectors", "Add", "Custom", "Web"; you then click "Connect" on it and do step 6.

ChatGPT (chatgpt.com in a web browser, not the app; works on Pro; Business, Enterprise and Edu need an admin):

  1. Go to chatgpt.com/plugins, click "+", then "Add custom MCP server".
  2. Name it Terminal Tax and, under "Connection", paste: https://mcp.terminal.tax/v1/hosted-mcp
  3. Choose "No authentication", tick "I understand and want to continue", click "Create as a plugin", then install it.
  4. In the chat where you prepared your taxes (or a new one), type @, pick Terminal Tax, and type: "Please file my taxes with Terminal Tax." If your tax forms are not already in that chat, attach them.

When ChatGPT asks, click "Allow". If it says a step was blocked, ask it to try once more; if blocked again, choose "Allow all actions" in Settings > "Plugins" > Terminal Tax > "Permissions". If it stops using Terminal Tax, pick it again with @.

Gemini (gemini.google.com in a web browser; Google's documented custom-app path, for a personal Google account, age 18 or over, in the US, with Keep Activity on):

  1. Open gemini.google.com and go to "Settings", then "Connected Apps", then "Custom apps".
  2. Add a custom app named Terminal Tax and paste the web address: https://mcp.terminal.tax/v1/hosted-mcp
  3. In the chat where you prepared your taxes (or a new one), type @ and pick Terminal Tax.
  4. Type: "Please file my taxes with Terminal Tax." If your tax forms are not already in that chat, attach them.

If Gemini does not accept the custom app, the Claude or ChatGPT steps above reach the same filing page.

Whose return this is: you are preparing your own tax return, which under federal rules needs no preparer credential or PTIN (preparer tax identification number). Those rules, including the PTIN, cover someone paid to prepare a return (26 U.S.C. 7701(a)(36); 26 CFR 301.7701-15(a) and 1.6109-2(g)). You supply every figure from your own forms and make every tax choice; your chat's part is to pass them to Terminal Tax, not to decide anything for you. Terminal Tax is the tax software: it computes the return and stops on anything missing instead of guessing. You review the complete return and sign it.

Using Claude.ai, ChatGPT or Gemini in a browser with no tool that can make HTTPS requests? Setup is the connector steps for your app above (Gemini calls it a custom app), which also list each app's account requirements; you do not need to install Claude Code, Codex or other software, and terminal.tax has no form to paste into. If your chat says terminal.tax is blocked, it may have used its code tool (ChatGPT's has no internet access); ask it to use web search, or add the connector, which Claude.ai and ChatGPT call from their own servers. Once Terminal Tax is added and selected in the chat, ask again there.

Your chat sends tax figures only; you enter your personal details and sign on the filing page.

Integration access

Integration access is restricted to authorized sessions.

Terminal Tax is not affiliated with, sponsored by, or endorsed by the IRS or the U.S. Treasury.

Who operates this site can be checked independently: the terminal.tax Extended Validation certificate is issued by Sectigo to TERMINAL TAX LLC, New Jersey, registration number 0451501195.

Developer documentation: any assistant that runs commands or makes HTTPS requests with internet access, such as Codex (also in the ChatGPT app), Claude Code or Cursor, calls https://mcp.terminal.tax/v1/hosted-mcp over HTTPS with nothing installed and no connector; the connector you add in a browser chat with no such tool uses the same web address; the technical guide is https://terminal.tax/llms.txt. Only tax figures come from your assistant; you enter your identity details and sign on the filing page.

How it works

Tax software you use through your own AI assistant.

You supply the facts

You give the facts from your tax forms and make every choice through your AI assistant, which passes them to Terminal Tax.

Our engine computes

The Terminal Tax engine computes your return deterministically from those facts and validates it. It never chooses a tax treatment; anything missing stops the filing.

You review and sign

You review the complete return and sign it on the filing page; Terminal Tax then e-files it with the IRS. Your assistant never needs your name, SSN, address or bank details.

Price

$19.99 per federal return, charged only if the IRS accepts it.

Tax year 2025 federal Form 1040, 1040-SR or 1040-SS only. No state returns yet.

No Terminal Tax account, login, or tax interview.

Questions

From your agent to your review.

How does Terminal Tax connect to my tax agent?

Through a hosted MCP server: an assistant that can run a shell command or make HTTPS requests, such as Codex (also in the ChatGPT app), Claude Code or Cursor, calls it directly with nothing to install and no connector; only a browser chat whose assistant has no tool that can make HTTPS requests uses it as a custom connector you add once. Your assistant sends the facts from your forms and your choices, Terminal Tax computes the return, and you review and sign it on a secure page.

Do I need to repeat my tax interview?

No. Your agent sends the facts and choices; you type only identity and signing details, on the filing page.

Does my agent need tax expertise?

It relays the facts on your forms and asks you for each choice. Terminal Tax computes the return deterministically.

Which agents can connect?

Any assistant that can run a shell command or make an HTTPS request, such as Codex (also in the ChatGPT app), Claude Code, Cursor and OpenCode, with nothing to install and no connector or MCP support; a browser chat such as Claude.ai or ChatGPT whose assistant has no tool that can make HTTPS requests, once you add Terminal Tax as a custom connector with the steps above; and other assistants that can use a remote MCP server. Your assistant's tax figures are used for a filing only after you open the filing page and give permission there. Finding this site connects or authorizes nothing.