ABC News' Lasa Hasan and Carolyn Durand report:
Buckingham Palace declined to give details on William's celebration, saying that the Duke of Cambridge will mark his 30th birthday with a "low-key" and "private" affair. But royal insiders say it's likely that he will gather with a few friends over a quiet dinner outside of London.
"He's turning 30, different things matter, different things are important," said ABC News royal contributor Victoria Arbiter, noting that this year's festivities are sure to be tamer than his African-themed 21st birthday blowout that made headlines. "He has a very close, very loyal circle of friends and chances are he'll be celebrating with them and they'll be keeping tight lipped."
William's newlywed bride turned 30 in January and despite speculation that her party planner sister Pippa Middleton, was throwing her a blowout bash befit for a princess, the palace said the Duchess of Cambridge celebrated with a "low-key and private" event as well.
If William's milestone birthday wasn't reason enough to celebrate, the future king is set to receive a large cash inheritance from his late mother Princess Diana's estate this year.
According to Diana's will which was made public, William and his brother Prince Harry are to inherit an equal amount of money as well as some of her personal belongings, including jewelry, dresses and more.
Arbiter estimates William's share of the inheritance to be around $14 million, but don't expect to see the royal couple splurge on flashy items or make major changes to upend their signature low-key lifestyle.
"That's a big chunk of money, but William leads a very normal life. He lives off his RAF salary, and we're not going to see anything grand or over the top," Arbiter said.
William, who is a search and rescue pilot in the Royal Air Force (RAF), has been kept busy this week with an RAF training course, and will attend the course Thursday too.
As for his birthday present, the royal rumor mill is in overdrive about what Kate could possibly get the future king of England. No pressure, Kate!