Fax a form to the IRS with an AI assistant

A worked example: the AI assistant prepares the fax with the HTTP call, and the person pays through the link.

This guide is a worked example for an AI assistant that can make HTTP calls. The person has a signed IRS form (for example Form 2848, Power of Attorney) and needs to fax it to the IRS. The assistant prepares the fax; the person adds the signed form on the web form and pays.

The main-site page for this case is payperfax.com/send-fax-to/fax-irs/. The service is described on payperfax.com/fax-api/.

Before you start

1. Get the fax number from irs.gov

   IRS fax numbers depend on the form and the person’s state. Look up the number for the form on irs.gov, on the form’s own instructions page. Show the source to the person before you send.

   Do not guess the number and do not use one from a third-party directory. The person’s own IRS notice is also a valid source.

2. Ask for the person's email

   The confirmation and the receipt go there. Ask the person for the address. Do not guess it.

3. Do not retype the signed form

   The signed form is a file. Do not retype it as text. A typed copy of a signed form is not the form.

Prepare the fax

The person has the signed form on their own device. You do not have the file. So you call the create endpoint with file_expected=true: the answer is a link to the web form, with the fax number already filled in. The person adds the file there.

curl https://fax.payperfax.com/api/fax \
  -F "to=[phone]" \
  -F "email=[e-mail]" \
  -F "file_expected=true"

The number above is an example. Use the number from irs.gov for the form the person is sending.

The answer is 200 with only url:

{
  "url": "https://fax.payperfax.com/fax/start/Jq3kV0c2mXb7RtY9pLs4HnW1eZa6UdG8fQi5oKjT"
}

Give url to the person. The link opens the web form with the IRS fax number already filled in and a notice that the AI assistant prepared the fax. The person uploads the signed form, sees the preview with the price, and pays. The link is good for 24 hours.

If you also wrote a cover letter

If the person needs a short cover letter (for example “Attached: Form 2848 for tax year 2025, signed 2026-04-15, from Jane Doe, SSN XXX-XX-1234”), write it as Markdown and send it in the same call. The letter becomes letter.md, the first document of the fax; the signed form is added by the person on the web form and goes after it.

curl https://fax.payperfax.com/api/fax \
  -H "Content-Type: application/json" \
  -d '{
    "to": "[phone]",
    "email": "[e-mail]",
    "markdown": "# Form 2848 cover letter\n\nFrom: Jane Doe\nDate: 2026-04-15\n\nAttached: Form 2848 (Power of Attorney) for tax year 2025, signed 2026-04-15.\n\nPlease process at your earliest convenience.\n\nJane Doe",
    "file_expected": true
  }'

A fax has no cover page unless you ask for one. So the letter must carry its own names, date and address block at the top.

The same call over MCP

If the AI app has the PayPerFax MCP server connected, the same call is the tool create_fax, with the same fields. Set to to the IRS fax number for the form, email to the person’s address, file_expected to true for a signed form, and markdown for the cover letter. The answer is the same url. MCP has no file transfer, so a signed form is always added by the person on the web form.

{
  "to": "[phone]",
  "email": "[e-mail]",
  "file_expected": true,
  "markdown": "# Form 2848 cover letter\n\nFrom: Jane Doe\nDate: 2026-04-15\n\nAttached: Form 2848 (Power of Attorney) for tax year 2025, signed 2026-04-15.\n\nPlease process at your earliest convenience.\n\nJane Doe",
  "country": "US"
}

Set country on the MCP call for the currency of the price shown on the preview. The HTTP call picks the currency from the caller’s IP by default; the MCP call reaches us from the AI app’s server, so without country it defaults to USD.

After the person pays

Once the person pays, the fax enters sending. Poll the status endpoint every 15 seconds and stop when is_terminal is true. The person is not charged if the fax fails to deliver.

See Check the status for the full list of fields and the polling rules.

What to tell the person

• The link opens the web form. You add the signed form there.
• Nothing is sent and nothing is charged before you pay.
• A failed fax is not charged. If the IRS line is busy, you can try again.
• The link is good for 24 hours.

Related

Send a fax

Create call reference

Check the status

Status values and polling

Page for AI assistants

The rules in plain language

Fax the IRS

Main-site page for faxing the IRS