The document states: "Upon the settlor's death, the entire principal of the Trust … shall be promptly distributed by the Trustee to the trustee or co-trustees of the BJS Kids & Family Trust, to be held, administered and distributed in accordance with its terms."
The "SJB Revocable Trust" was reportedly created in 2004, four years prior to when her conservatorship started in 2008.
Britney's trust reportedly includes her bank accounts and personal items such as clothes, jewellery, artwork and furniture. It's not clear if it also includes the value of any of her intellectual property, such as music rights.
Last week Britney Spears failed to remove Jamie Spears from controlling her business and personal affairs when a Los Angeles court refused to make immediate changes to her 12-year conservatorship, according to the Mirror.
She had asked for her care manager to replace her father as her conservator, but the court extended the existing arrangements until February 2021.
Britney's fans have campaigned for years for Britney to be released from the arrangement, in a movement called #FreeBritney.
The star's father was made her conservator in 2008 when she was hospitalised for psychiatric treatment.
She had asked a judge to replace him with an independent professional conservator, Jodi Montgomery, who took over from Jamie last year when he suffered a health crisis.