Short answer: a chat assistant cannot send a fax on its own. ChatGPT, Claude and Gemini are chat windows. They have no fax number, no telephone line and no way to dial out. They also have no credit card to pay with, and no way to mail you one when the fax finally lands. If you ask one of them to “fax this to my doctor,” it cannot. Not today, not with a paid plan, not with a workaround.
What is possible, and what the rest of this page is about, is subtler and more useful: an AI assistant can prepare a fax, and you can send it. The assistant drafts the letter, finds the destination number, hands you a link, and you pay in the browser. The fax goes through PayPerFax, same as if you had typed everything yourself. The person-at-a-browser step stays where it is, because that is where the payment and the final check live.
The rest of this page covers the real options, in order of what you have in front of you.
1. If you only have a chat app (ChatGPT, Claude, Gemini)
A plain chat window with no attached tool is the most common case. You open ChatGPT in your browser, or the Claude app, or Gemini, and ask it to help with a fax. It cannot press “send” for you, but it can do everything up to that point.
Ask it to write the letter. A change-of-address notice to a servicer, a cover sheet for an IRS form, a short authorization: these are the easy wins. The assistant drafts the text in seconds and will edit it with you until it reads the way you want. Ask for the full letter and the fax cover sheet together.
Ask it to hand you the document as a file. ChatGPT, Claude and Gemini can all produce a document and let you download it as a PDF, a DOCX or a Markdown file. “Give me this as a PDF I can download” is the sentence to use. The file lives on your computer afterwards.
Open PayPerFax and upload it. Go to fax.payperfax.com, enter the destination fax number, upload the file the assistant made for you, review the preview with the final price, and pay. PayPerFax accepts PDF, DOC, DOCX, JPG, PNG, TIFF and Markdown files up to 10 MB total.
That is the honest, works-today path for a conversation that happens entirely inside a chat app.
If the assistant can read web pages (ChatGPT with web browsing, Claude with web access, Gemini), it can also read the tracking page after you pay. Paste the tracking URL from your confirmation email into the chat, and the assistant will tell you when the fax lands.
2. If your assistant can send through the PayPerFax API (coding agents)
A coding agent that lives inside a terminal is a different story. Claude Code, Codex and Cursor all run commands in a shell. Any of them can send the fax for you through the PayPerFax API. The agent gives PayPerFax the destination number, your email address, and either a letter it wrote or a file it has on disk. It gets back a payment link. The agent hands you the link. You open it, see the preview with the final price, and pay. The agent never pays. There is no account for it to make and nothing for it to register.
For a signed form the agent does not have (a 2848, an SS-4, a bank authorization that needs your signature), the agent can still prepare the fax without the file. The link opens the fax form, pre-filled with everything the agent knows, with a short notice that reads “Your AI assistant prepared this fax.” You add the signed page yourself and continue in the browser.
The reference for an assistant that is making the call lives on the PayPerFax documentation site.
3. If your assistant has our MCP server connected
Some chat apps let you attach a Model Context Protocol (MCP) server as a custom connector. PayPerFax runs one at https://fax.payperfax.com/mcp. You add it once in the chat app’s connector settings; there is no password and no key. When you add the server, the assistant can prepare a fax, check its status, and list what you can send – right inside the chat. You ask in plain language (“fax this letter to the clinic at this number”), the assistant prepares the fax, and it hands you back the payment link. The link opens in your browser; the person-at-a-browser payment step is kept.
Claude was the first chat app to ship native MCP connector support. ChatGPT, Gemini and other chat apps are catching up as the standard spreads; coding agents such as Claude Code, Codex and Cursor can also talk to MCP servers alongside their shell. Setup lives on the PayPerFax documentation site.
MCP has no file transfer. A letter the assistant writes goes as Markdown text in the call. A signed form or a scan is still added by you on the web form, the same as a chat app with no connector.
What each app can do today, at a glance
| Kind of app | Examples | What it can do today |
|---|---|---|
| Chat app, nothing installed | ChatGPT, Claude, Gemini | Writes the letter and gives it to you as a file. You upload it on the PayPerFax form. If the app can read web pages, it can read the tracking page too |
| Coding agent with a shell | Claude Code, Codex, Cursor | Sends the fax for you through the PayPerFax API: either a letter the agent wrote, or a file it has on disk. Gives you the link to pay |
| Chat app with our MCP server | Claude (native MCP connector); other chat apps as they add MCP support | The assistant prepares the fax from inside the chat window. The payment link still opens in your browser. No file transfer: a signed form is added by you on the web form |
| Email-reading assistant | Gemini in Gmail and similar | Not supported yet. The email door is in design |
Nobody at PayPerFax has sat down and tested every one of these apps end-to-end. Our best picture of what works is in the table above. If one of them does something different from what you see here, tell us so we can fix the page.
Three rules worth keeping
Whatever assistant you use, three habits make the difference between a fax that lands and one that bounces.
Give the assistant your email address, do not let it guess. The email address is where PayPerFax sends the confirmation. The assistant does not know yours unless you tell it. If you leave it blank or let the assistant invent one, the confirmation goes nowhere.
Take the destination fax number from the official source. For the IRS, the number comes from your notice or from irs.gov. For a bank, from the bank’s own site or from a letter they sent you. For a doctor’s office, from a bill or a form they handed you. An AI assistant can look up a fax number, but the one you trust is the one on the paper. Cross-check before you send.
A signed form stays a file. The signed page on a 2848, a power of attorney, a lease, a medical release: the IRS and every other agency needs the actual signed page, not a typed copy. If the assistant tries to retype the form as text, stop it. Scan the signed page and send it as a file, or let the assistant prepare the fax without the file so you can add the scan in the browser.
Frequently asked questions
Does the AI assistant pay for the fax?
No. The assistant prepares the fax and gives you a link. You open the link, see the preview with the exact price, and pay with a card or PayPal. Payment is always a person at a browser, every time. This is deliberate: it is also what keeps the service from being used for spam faxes.
Can an AI assistant send a fax from inside my email?
Not today. An assistant that reads your email (Gemini in Gmail, Copilot in Outlook) cannot yet forward a message to a fax number through PayPerFax. The email door is in design and will be announced on the PayPerFax API page when it ships.
Which assistants work with this?
Any assistant that can either (a) talk to our MCP server as a custom connector (Claude first; other chat apps as they add native MCP support), (b) run commands in a shell (Claude Code, Codex, Cursor and any script you write), or (c) produce a downloadable file (ChatGPT, Claude, Gemini on their own). The first two groups prepare the fax directly through the PayPerFax API; the third writes the letter for you to upload at fax.payperfax.com.
Is it safe to let an assistant start a fax for me?
The assistant only prepares the fax. It cannot pay. It cannot send without you. Every fax has a preview link that only you open, and the preview shows the exact document and the exact fax number before you pay. Documents are deleted from PayPerFax within 30 days. The full policy is on the security page.
How much does it cost?
The same as any other fax through PayPerFax: $2 for the first three pages (one optional cover page and two document pages) and $0.75 for each page after that. The preview link shows the final guaranteed price before you pay. A fax that fails to transmit is not charged.
What if the assistant writes the wrong fax number?
That is the single most common mistake. Always cross-check the number against your IRS notice, your bank statement, your doctor’s letter or the agency’s own website. The preview page shows the number the fax is about to go to; read it before you click pay.