Spirit Airlines' official policy is to "do its best" to seat children with at least one accompanying adult, but they do not guarantee it unless you pay for seat assignments in advance. In 2026, Spirit uses an automated system that attempts to keep families together during the check-in process, but if the flight is nearly full, a child could theoretically be assigned a seat away from their parents. To avoid this, Spirit strongly recommends that families purchase seats during the booking process. If you choose not to pay and find your family separated, you must speak to a gate agent or flight attendant; however, they rely on the "kindness of strangers" to swap seats, which is not always successful. It is important to note that the U.S. Department of Transportation has increasingly pressured airlines to ensure fee-free family seating, but as a "Ultra Low-Cost Carrier," Spirit's business model still prioritizes paid seat selection for guaranteed proximity, making it a "gamble" for those trying to save on ancillary fees.