His brother Prince William received his own share on his 30th birthday two years ago. Harry is set to receive slightly more because of the interest that has accrued in that time.
The boys were left the money under a will created by the Princesss in 1993. The document stipulated that they would be bequeathed it at the age of 25. Details of the will were changed three months after her fatal accident in 1997 via an order in London's High Court.
When she died Diana left nearly £13 million which was reduced to £8.5 million after death duties. It's thought the fund then swelled to more than £20 million thanks to clever investments by royal advisors.
Her estate included the settlement she got on her divorce from Prince Charles. This comprised stocks and shares, jewellery, cash from her £17-million divorce settlement, dresses and other personal belongings from her Kensington Palace apartment.
Harry, who currently earns £38,847, will be in line to pay up to £4 million in duties. Another consequence of him reaching 30 is that the Princess' wedding dress is being returned to her sons.
Diana had asked that some of her most cherished possessions, including her magnificent wedding gown, be kept her brother Earl Spencer.
She requested that her belongings be handed back to her sons when they turned 30.