Refurbishment of Prime Minster Tony Abbott’s official Canberra residence will cost taxpayers at least $5 million more than expected.

Work on The Lodge is set to be completed in July and will cost $8.842 million, dwarfing the original $3.19 million price tag.

With scope of the works expanded again, Finance Department officials have pushed back the completion date for the third time.

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Work on the historic Deakin home originally included asbestos removal, replacement of the slate roof, heating and cooling system upgrades, new lights and electrical wiring, painting, a new kitchen, bathroom improvements and health and safety upgrades, Fairfax Media reported.

Finance officials told Senate estimates in May the scope of works, overseen by head contractor Manteena, had been expanded to include security systems, “functionality and liveability” improvements to living areas and bathrooms and work on rundown external guard houses adjacent to the property’s walls.

The Lodge residence in Canberra. Photo: AAP

“Preparations are progressing for the move back into The Lodge but a specific date is yet to be identified as it is contingent on completion of exterior works,” a spokeswoman for the Department of Prime Minister and Cabinet told Fairfax Media on Monday.

“Once the interior works have been completed, the installation of soft furnishings, furniture, equipment and artworks is expected to take up to four weeks. The Lodge will be ready for occupation on completion of the external works.”

Fairfax Media revealed the job was originally commissioned under the former Labor government, but costs had grown steadily.

In April 2014, the bill was calculated at $4.45 million. By December, the contract was varied to $6.38 million. The Abbott Government’s first budget included unspecified extra funds for the work.

Meanwhile, a report released by the Department of Finance last week revealed Liberal MP Tony Pasin racked up the most expensive office refurbishment bill in the federal parliament.

The Mount Gambier-based politician blamed the $506,752 expenditure on lack of suitable facilitates within his electorate, for the second half of 2014.

In another costly blow, a building assessment on Parliament House last week showed it would need more than $300 million in upgrades during the next decade to meet with safety standards.

With much of the building’s infrastructure nearly 30-years-old, the 14-volume condition report found significant problems with its storm water drainage, toilets and chillers.