Around £150 million needs to be spent on a major revamp of Buckingham Palace, according to royal sources - and the Queen may need to move out while the work is done.
The full scale of the refurbishment project was outlined as the annual royal financial statement was released, revealing the monarchy cost the taxpayer a total of £35.7 million last year for the second year running - the equivalent of 56p per person.
The sum, known as the Sovereign Grant, will help pay for some of the works, though additional funding may be needed.
It has not yet been decided whether all the work will be done in one go, or broken down into a longer-term project - and which option is chosen will determine whether the Queen can remain in residence.
The historic building - first used as a royal palace by Queen Victoria - has not been redecorated since 1952, the year the Elizabeth II ascended.
Speaking to the Press Association, a royal source said:
An in-house palace team produced a 10-year property maintenance plan which revealed that work to the iconic building is likely to include replacing the ancient plumbing and the ageing electrical wiring, as well as removing a significant amount of asbestos.
The last time the queen left the palace for any significant length of time was during the Second World War, when she - then a princess - and her sister Princess Margaret were moved to Windsor Castle.
The financial statement revealed around half of the Sovereign Grant was spent on staff, and £11.7m on property maintenance. A £2.2m chunk was set aside to help pay for future re-servicing works on Buckingham Palace.
The cost of travel increased by £1m, the figures showed, but reductions elsewhere helped keep the overall cost the same.