Field to display once check-box is checked

Hi Mr. Peri,

What you’re looking for is usually called ‘Conditional Logic’ or ‘Conditional Fields’. Basically: IF someone selects X THEN make Y appear.

To help understand, there’s a good explanation and demo form to try in the CF7 Skins Knowledge Base Form Logic section. Also, Elegant Themes has an article on Contact Form 7 extensions, including one with logic. There is an image example showing exactly the scenario you described.

If you are a more advanced WordPress user, there is a tutorial on conditionally displaying fields with Javascript.

Otherwise, your option is to download an extension. Most of these are paid, but there should be a few free options. When searching for a plugin, try ‘form logic’ or ‘conditional’ in the search field for a wide range of results.

Good luck!