A donation form collects intent; taking the money is a payment system.

Two systems, one donation

Money moves on a payment provider; the record of who donated, how much, and what for lives with you. Trying to make one system do both is how charities end up storing card numbers in a spreadsheet. Split them deliberately and the reconciliation is a reference string.

<form action="https://freelyform.com/f/FORM_ID" method="POST">
  <input type="hidden" name="_subject" value="Donation intent">

  <label for="name">Name</label>
  <input id="name" name="name" autocomplete="name">

  <label for="email">Email (for the receipt)</label>
  <input id="email" name="email" type="email" autocomplete="email" required>

  <fieldset>
    <legend>Amount</legend>
    <label><input type="radio" name="amount" value="25" required> 25</label>
    <label><input type="radio" name="amount" value="50"> 50</label>
    <label><input type="radio" name="amount" value="100"> 100</label>
    <label>Other <input type="number" name="amount_other" min="1" step="1"></label>
  </fieldset>

  <label for="frequency">Frequency</label>
  <select id="frequency" name="frequency" required>
    <option value="once">One time</option>
    <option value="monthly">Monthly</option>
  </select>

  <label>
    <input type="checkbox" name="anonymous" value="yes">
    Give anonymously — do not list my name publicly
  </label>

  <button type="submit">Continue to payment</button>
</form>

The three fields that change the follow-up

• Frequency. A monthly donor needs a different thank-you, a different receipt, and a way to stop. Without it recorded, every recurring gift looks like a one-off.
• Designation. If gifts can be restricted, the option has to exist — but keep it to three or four choices, because a long list of funds is a decision the donor did not come here to make.
• Anonymous. A checkbox, not an empty name field. Somebody who wants to give without being listed will leave rather than guess what an empty name field will do.

The receipt is the form's real deliverable

For a donor, the email is the donation. It should state the amount, whether it repeats, and how to change it, and it should be possible to find months later. That argues for a specific subject line — including the reference — rather than "Thank you for your support".

What not to collect

Address, phone number, and date of birth are not needed to send a receipt. Each one is personal data you then have to protect, retain, and delete, and each one costs a completion. Ask for the email, and ask for a postal address only if you actually mail something.