Kate Middleton Sends Christmas Concert Invites Complete with Her Royal Cypher (and the Dress Code!)

Kate Middleton is gearing up for her third annual Christmas concert — and making sure her special guests are ready too!

Just one day ahead of the Princess of Wales' Together at Christmas carol service at Westminster Abbey, Prince William and Princess Kate's social media accounts shared a new video showing some of the lucky attendees receiving their invitations.

"Invites at the ready!" the team captioned the post. "Looking forward to tomorrow’s Carol Service with @earlychildhood and welcoming so many of you who make such a difference to children and families in communities across the country #ShapingUs."

Guests were filmed opening and reading their invitations, which were topped with Kate's royal cypher, a "C" for "Catherine" (her full name) topped with a crown.

The invitation also contained an important piece of information: the event's dress code. As in past years, the guidance for dress is "smart (no hats)."

Excited guests placed their invitation cards in special places, like on the fridge (secured with dinosaur magnets for two youngsters!) or in a Christmas tree.

This year's event is linked to Princess Kate’s Shaping Us campaign, which focuses on her mission to support children during the early years of their lives. The palace said the event was organized to “thank all those who work to support babies, young children and families in our communities across the U.K. and a celebration of the golden opportunity that the birth of a new baby brings."

Keeping with this year's theme, Princess Kate is likely to bring her three children to the event. While Prince George, 10, and Princess Charlotte, 8, accompanied their parents to the carol concert last year, it would mark 5-year-old Prince Louis' first time if he attends on Friday.

The Christmas concert will feature performances by Westminster Abbey's choir, Adam Lambert, Beverley Knight and more as well as readings by special guests, including Prince William!

The event will be broadcast as part of Royal Carols: Together At Christmas, airing on ITV1 and ITV X on Christmas Eve. The television broadcast will feature additional content including an introduction from Princess Kate, films that highlight the importance of early childhood and celebrations of the contributions people in our communities are making to support the very youngest members of our society during those crucial early years.

The inaugural Christmas concert hosted by Kate was held at Westminster Abbey on Dec. 8, 2021. The royal surprised viewers with her first public piano performance, accompanying Tom Walker as he sang "For Those Who Can't Be Here."

Can't get enough of PEOPLE's Royals coverage? Sign up for our free Royals newsletter to get the latest updates on Kate Middleton, Meghan Markle and more!

Though the Princess of Wales didn’t play piano at the 2022 show on Dec. 15, 2022, the festive event was again held to bring together members of the royal family with charity staff, community volunteers, frontline workers, military personnel and more to "celebrate the joy that human connection can bring," Buckingham Palace said.

Last year’s program was woven with tributes to Queen Elizabeth, who died in September 2022 at age 96.