Welcome to planDisney, Sydney! I'm so glad to be able to answer your question today. Celebrating your son's third birthday at Walt Disney World is going to be so magical, and I'm happy to let you know exactly how to navigate tickets for a
toddler!
Since you're planning to buy your ticket as part of a vacation package with a
Disney Resort Hotel stay, your son's ticket type is based on how old he is on your check-in day, not the day you first go into the parks. In your case, you're checking in the day before his third birthday, which means that, for ticket purposes, he is considered under 3 for the duration of your trip.
What that means in practice is that, with a vacation package, you do not need to buy a child's ticket for this visit. He will be considered under three age-wise for your whole vacation and can enter the parks with you without a ticket, even on and after his birthday during that same stay. One little thing to keep in mind: at places where age matters for pricing, like
buffets and family-style meals, he'll be considered whatever age he is that day, so once he turns 3, he'll be charged the regular child price at those locations.
The only time the ticket situation would change is if your plans shift and you decide to stay off-property instead of at a Disney Resort Hotel. In that scenario, your tickets wouldn't be part of a package, and your son would require
valid admission starting on the day he turns three.
I hope this answers your question, Sydney, and please let us know if there's anything else we can do to help you plan your magical vacation!
Jessica