Gangland matriarch Roberta Williams could soon lose her home as her family's Essendon house is set to be seized and sold off by the tax office following a Supreme Court ruling.

Roberta, the widow of murdered drug lord Carl Williams, on Wednesday lost her long-running dispute with the Australian Taxation Office over the estate of her father-in-law George Williams, who died in 2016 owing $576,000 in unpaid taxes.

George had left in his will his three-bedroom house in Primrose Street, Essendon, to granddaughter Dhakota – the daughter of Carl and Roberta – but the property was also pledged to the ATO as collateral for his debt.

Roberta and Dhakota Williams leave the Supreme Court after the ruling against her. Credit:Joe Armao

In March, the Supreme Court ruled Roberta had no claim to the house and made orders for it to be sold and the proceeds used to pay George's tax debt.