September 12 marks a major milestone for superstar Britney Spears.

Her youngest son Jayden turns 18 on Thursday — and sources close to the Princess of Pop have exclusively told DailyMail.com that while she’ll be celebrating, her ex-husband Kevin Federline may not be in the mood for cake and balloons.

Jayden’s 18th birthday, the Mail has learned, will trigger the cessation of child support payments that Spears has been paying to Federline for the care of their two children — Jayden and Sean Preston, 18 — for the past 17 years totaling more than an estimated $5 million.

‘The amount of money Britney has given Kevin for the two boys is extraordinary and it is enough for any man to support an entire family, which is what she believes he has done,’ the source close to Spears told The Mail.

The sense from Britney world is that Federline, 46, a former backup dancer for Justin Timberlake and failed pop performer who now occasionally works as a DJ, will struggle to maintain the lifestyle that he’s become accustomed to.

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Thursday marks a major milestone for Britney Spears – as her youngest son Jayden Federline (pictured) celebrates his 18th birthday.

Jayden’s 18th birthday will trigger the cessation of child support payments that Spears has been paying to Federline for the care of their children, Jayden and Sean Preston  (pictured).

The Mail reached out to Federline’s lawyer to respond to these allegations but did not receive a response.

Whatever happens to Federline, Britney views it as his problem to solve, the Mail is told.

‘Britney is hearing that he is not a happy camper,’ the sources said, while ‘Britney is living her best life.’

She is certainly not in want of money.

According to sources, a financial windfall from her best-selling tell-all memoir, ‘The Woman in Me’ and a deal with Universal Pictures to turn it into a movie has been transformative – allowing Spears to move beyond some of her struggles and unleash a new creative energy.

‘This film has allowed her to get outside of her head,’ the source told the Mail. ‘She is considering creating new music for the soundtrack but that is still preliminary.’

What’s more, Britney is allegedly expunging supposed negative influences from her life, including her former housekeeper-turned-boyfriend Paul Soliz.

‘She has rid herself of all toxic people,’ the source said.

When it comes to her children, Spears is excited at the prospect of ‘having her boys back.’

‘The amount of money Britney has given Kevin (right) for the two boys is extraordinary and it is enough for any man to support an entire family, which is what she believes he has done.’

Federline, 46, former backup dancer for Justin Timberlake, now only occasionally works as a DJ, and has received an estimated $480,000 a year in child support payments since 2018.

And while those close to Spears reveal that she is disappointed that she will not be with Jayden on Thursday because he is currently living in Hawaii and ‘will likely be having a celebration with his friends’, they say Spears is going to get him a gift that ‘is more expensive than anything his father could afford.’

As far as Spears’s relationship with Federline – that’s a different story.

Court documents show that since 2007 Federline has received $240,000 per year for the care of Jayden and Sean Preston until 2017 – and then, according to sources, that amount was increased by court order to $480,000 per year.

Federline now lives on the island of Oahu in Hawaii with his third wife Victoria Prince, whom he wed in 2013.

Jayden, Sean Preston and Federline’s four other children – two of whom he fathered with Prince and two with his first wife, Shar Jackson – now live with him in a rented $14,000-a-month, five-bedroom, 6,300 square-foot home that has a listed sale price of $3.7 million and sits a few blocks from the sea in the picturesque, luxury suburban community of Portlock, Oahu.

Indeed, a sprawling mansion in Portlock is a far cry from where Federline found himself in 2007 after divorcing Spears, citing ‘irreconcilable differences.’

That year, he was granted custody of their boys by a California court – as Spears struggled with a public breakdown and was later placed under a restrictive conservatorship in 2008.

Britney, who was then living in a palatial Los Angeles mansion, was ordered to pay $10,000 a month per child to Federline.

In 2018, Kevin revealed the extent of his financial woes as part of a legal appeal for Spears to increase her payments to $20,000 a month per child.

‘I am no longer able to perform as a dancer due to my age, and I have not been as successful in putting out new music as I was in 2008,’ Federline represented in court documents.

Federline claimed that he earned $3,000 a month through his DJ work, had no health insurance, no stocks or assets and no savings.

Kevin and Britney met in a club the summer of 2004 when Britney was at the peak of her fame, and married months later.

Spears has sent Federline an estimated $5million for the two boys’ – Jayden and Sean Preston, 18 – care since 2007.

I am simply less of a “name” and less in demand than I was in 2008, which has negatively affected my income.’

Federline also claimed that he and Victoria, who he was dating at the time, were crammed into a 2,000-square-foot home with Jayden, Sean Preston, and his four other children.

‘Sean and Jayden have to share a room at my house,’ he wrote in court papers, ‘There is no room for them to invite friends over or to have sleepovers.’

Spears, he claimed, ‘is a single woman who lives alone in a 13,264 square foot Neoclassical Italianate villa on 21 acres of land in a gated community with an elevator, a library, a media/game room, 3,500 bottle wine cellar, an additional 1,200 square foot pool house, an orchard, resort-sized pool and spa, lighted tennis court and three-green golf course.’

‘There is a library, a media room, a game room, private chefs, tutors, housekeepers, ATVs and all the latest gaming systems, entertainment systems and technological gadgets. I simply cannot even come close to providing parity for our children in my modest home,’ he wrote.

Kevin moved to Hawaii with his family in August 2023 claiming there were DJ-ing opportunities for him and Prince was hired as an assistant volleyball coach at the University of Hawaii.

Federline now lives with his third wife Victoria Prince (pictured), whom he wed in 2013, Jayden, Sean Preston and his four other children in their rented Hawaii home.

‘[Britney] takes our minor children on multiple lavish vacations per year, including trips to five-star resorts in Maui, one of the Hawaiian islands. I have not been able to take the children on a vacation in years.’

By Federline’s own admission, he was living a life that paled in comparison to the glamorous early days of his three-year marriage to Spears.

They met in a nightclub during the summer of 2004 when Spears was at the peak of her fame and married months only later, becoming media darlings who had their own reality show, Britney & Kevin: Chaotic.

After the divorce Federline’s career appeared to flounder. He tried his hand at modeling, music and even professional wrestling, but struggled to establish himself in any of those pursuits.

In the 2010 season of VH1’s weight-loss reality television show Celebrity Fit Club, he spoke openly about his struggles and blamed his poor health on depression and his divorce from Spears.

Federline moved with his family to Hawaii in August 2023 claiming there were DJ-ing opportunities for him there. His wife Victoria Prince was hired as an assistant volleyball coach at the University of Hawaii.

In the years since, sources close to Spears, say she has been working diligently to rebuild her relationship with her young sons.

After Spears’ conservatorship ended in November 2021, the boys distanced themselves from their mother and reportedly stopped replying to her texts.

Whatever lifestyle changes Kevin is forced to make when child support payments stop this week, Britney will not let her children suffer as a result, sources say.

Britney Spears posts with her two sons Sean, aged nine, and Jayden, aged seven, and her younger sister Jamie Lynn, 23, and her six-year-old daughter Maddie on Instagram.

Jayden gave an interview with ITV in 2022 and said: ‘It’s almost like [Spears] has to post something on Instagram to get some attention. This has gone on for years and years and years and there’s a high chance that this will never stop, but I’m hoping for me that she will stop.’

In a now-deleted response, Britney criticized her son’s statement and even referenced the child support payments, saying: ‘Do you guys want me to continue to get better so I can continue giving your dad 40 grand a month?

‘Or is the reason you guys have decided to be hateful is that it’s actually over in two years and you don’t get anything?’

Now, sources tell the Mail that any strife between mother and sons is in the past: ‘In terms of her boys Sean and Jayden, they know that she would do the world for them, but she will be very careful to make sure any money she gives to them will not be handed over to their dad.’

‘Britney is doing extremely well right now,’ the source said. ‘She has plenty of money to live how she wants for the remainder of her life.’