How to split the bill if it's someone's birthday

Between balloons, cake, and an outpouring of excitement, birthday celebrations can be counted on for a good time. But as adults, most of us have graduated from backyard parties and over-the-top decorations to more low key options, such as a nice lunch or dinner out with close friends.

While these outings may be simpler to organize, the same question usually arises at the end of the night: Who's paying?

Should the attendees cover the guest of honor's cost? Is the birthday boy or girl expected to treat their guests?

The answer is rarely cut and dry, but as a general rule it comes down to who called for the event.

"Generally when it's the friends saying 'Let's all get together and celebrate Mary's birthday,' everyone except Mary pays for lunch," explains Patricia Napier-Fitzpatrick, founder and president of The Etiquette School of New York. "But sometimes someone wants to have their own birthday luncheon, so let's say Mary invites everyone to celebrate her birthday with her, in which case she would pay for everyone, but everyone should bring a gift for her."

While the host isn't always expected to pay for every guest's meal - always bring enough cash to cover your own order to be safe - if a friend arranged their own birthday outing, you shouldn't feel obligated to pick up their tab.

"If you are throwing your own celebration, you should also pay," Diane Gottsman, national etiquette expert and the owner of The Protocol School of Texas, told Business Insider.

In short, if you planned your own birthday dinner, don't expect your friends to pay for you. But it's a nice gesture if they offer to anyway.

But if the situation is reversed and everyone decides to take out a friend for their birthday, go ahead and foot the bill for the guest of honor.