The 33-year-old actress has filed for divorce from the 49-year-old actor - who she wed in November 2006 - and as she had signed a pre-nuptial agreement before they tied the knot, she is unable to seek half his rumored $275 million fortune.
Instead, she will reportedly be paid $15 million for the five-year union as well as being given their $35 million Beverly Hills mansion.
However, Katie - who has cited "irreconcilable differences" as the reason behind their split - is seeking sole custody of the couple's six-year-old daughter, Suri, and experts believe she will get a huge amount of child support from Tom.
Top divorce attorney Vikki Ziegler told Hollywoodlife.com: "Most of the estate is Tom's. She'll have to go for a lot of child support. She'll have to show that Suri has nannies, cars, activities, clothes, hair appointments. That a hefty amount each month is needed to maintain Suri's lifestyle."
Once the divorce is finalized both Katie and Tom will keep their respective earnings from the projects they've worked on since November 2006.
As well as the Beverly Hills mansion, the former couple also have homes in New York, Colorado, Italy and England.
Since they did not stay married for 11 years, the pre-nuptial agreement states California community property laws won't apply to the divorce - which normally sees a couple's assets split 50/50.
Following the news Katie was filing for divorce, Tom - who has two children, Isabella, 19, and 17-year-old Connor with ex-wife Nicole Kidman - said he was "deeply saddened" by it.
Sources claim Katie had given no indication to Tom - who was also married to actress Mimi Rogers - she was going to do it.