Title: Required answers and validation | OneForm > Make questions required, and see how OneForm checks emails, phone numbers, numbers, dates and other answers before a form is sent. Source: https://oneform.si/help/forms/required-answers-and-validation/ --- 1. [Help Center](https://oneform.si/help/) 2. [Forms](https://oneform.si/help/forms/) 3. Required answers and validation [View as Markdown](https://oneform.si/help/forms/required-answers-and-validation.md) # Required answers and validation Make questions required, and see how OneForm checks emails, phone numbers, numbers, dates and other answers before a form is sent. Admins and ownersUpdated October 22, 2026 · 2 min read A required question has to be answered before the client can move on. OneForm also checks the format of some answers, such as emails and dates, so you don't get answers you can't use. ## Make a question required 1. In the builder, select the question. 2. In the side panel's **Content** tab, under **Settings**, turn on **Required**. A pink star appears next to the question in the list. Statements have no **Required** switch, because there's nothing to answer. For **Contact info** questions, each part (first name, email, phone…) has its own **Required** box. If you make the whole question required but none of its parts, clients must fill in at least one of them. ## What OneForm checks | Question type | The answer must be | Clients see | | --------------------- | ------------------------------------------------------------- | -------------------------------------------------- | | **Email** | A real-looking email address | "Hmm… that email doesn't look right" | | **Phone number** | A phone number with a sensible number of digits | "Hmm… that phone number doesn't look right" | | **Number** | A number. Commas, spaces and dollar signs are fine | "Please enter a number" | | **Date** | A real calendar date | "Please enter a valid date" | | **Multiple choice** | One of the options. With **Other**, the box must be filled in | "Please fill in the 'Other' option" | | **Line items** | A description and an amount on each line | "Please add a description and amount on each line" | | Any required question | Answered | "Please fill this in" or "Please choose an option" | These messages appear in the client's language when your form offers English, French and Spanish. OneForm checks answers again when the form is sent, so the same rules apply to forms on your website. ## Good to know - **Hidden questions are never required.** If a "show only if" rule hides a required question, clients skip it. See [Logic and branching](https://oneform.si/help/forms/logic-and-branching/). - **Dynamic forms** require only the questions OneFormAI actually asks. See [Dynamic forms](https://oneform.si/help/forms/dynamic-forms/). - **Voice forms** call required questions **Needed**. See [How voice forms work](https://oneform.si/help/forms/how-voice-forms-work/). - **There are no custom patterns.** You can't set your own formats, word counts or minimum lengths. To limit answers, use a **Multiple choice** or **Yes / No** question instead of text. - **Line items** take as many lines as **Maximum lines** allows. ## Why can't my client submit the form? - **A required question is empty.** Clients can't move past it until it's answered. Check that it's a question every client can answer, or make it optional. - **An answer is in the wrong format,** like a phone number with too few digits. The message under the question says what to fix. - **They chose Other but left it blank.** Type something in the **Other** box, or pick another option. ## How do I make a question optional again? Select it and turn off **Required**. The change saves right away, and a published form picks it up within a few seconds. Was this article helpful? [← PreviousQuestion types](https://oneform.si/help/forms/question-types/)[Next →Logic and branching](https://oneform.si/help/forms/logic-and-branching/) ## Related articles [Question typesEvery kind of question you can add to a form, what clients see for each, and when to use it.](https://oneform.si/help/forms/question-types/)[Logic and branchingShow questions only when they apply, skip ahead based on answers, add up scores, and send people to different endings.](https://oneform.si/help/forms/logic-and-branching/)[Dynamic formsLet OneFormAI choose the most useful next question for each client from your list, so people answer fewer, better questions.](https://oneform.si/help/forms/dynamic-forms/)[How voice forms workWhat your clients see and hear in a voice form, how it handles unclear or skipped answers, switching to typing, and what's kept.Pro plan and up](https://oneform.si/help/forms/how-voice-forms-work/) Still stuck? A person on the OneForm team reads every request. 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