Harry and Meghan have only been spotted out and about on rare occasions, most recently when they were photographed getting into a Cadillac SUV wearing face masks.
According to the insider, Meghan's guest list would be limited to her nearest and dearest friends and the festivities would be held outside.
The Duchess of Sussex would also require anyone who attends to get a fast-tracked COVID-19 test.
"Whatever she ends up doing for her birthday, Meghan said it will be low-key. She said she doesn’t want to come across as being careless and irresponsible," the source explained.
Meghan's 39th birthday celebrations will look significantly different compared to what she did last year.
For her 38th birthday, the Duchess of Sussex was still a senior royal, but kept things low-key at Frogmore Cottage in Windsor with her family.
Meghan also received a gourmet carrot cake from Stoke Newington-based Luminary Bakery.
What's more, Westminster Abbey traditionally rings its bells to mark senior royals birthdays, but since Meghan has stepped down, it's expected they will not ring on August 4.
“I hear that Westminster Abbey will not ring its bells for Meghan’s birthday next month,” The Daily Mail’s Richard Eden speculated in a recent article, before reflecting on how troubled Prince Andrew still managed to receive the honour.
“They are due to ring for Princess Anne’s birthday, 11 days after Meghan’s. And they will chime again to celebrate the Duchess of Cambridge turning 39 in January,” he added.
“The bells are usually rung to mark the birthdays of senior members of the Royal Family, and through the line of succession to the Duke and Duchess of Cambridge and their children," a Westminster Abbey spokesperson revealed.
