UPDATE | UK Labour leader says coronavirus inquiry is inevitable
However, the State Rooms at Buckingham Palace, Frogmore House and Clarence House will stay shut over the summer months "owing to the operational challenges of social distancing".
The Royal Collection Trust, which looks after the Royal Collection of art and manages public access to the official residences, has reportedly suffered a major drop in income that has forced it to plan voluntary redundancies.
It had been expected to make 77 million (85.6 million euros, $96.5 million) this year, but the lockdown has caused its earnings to fall to 13 million, according to the Daily Telegraph, citing an internal memo.
Visitors to the royal residences will be asked to book tickets in advance and new measures have been introduced, including one-way routes, to maintain social distancing to limit the spread of coronavirus.