The Kremlin’s spokesman Dmitry Peskov says a big inheritance explains why he earned four times more than President Vladimir Putin in 2015, according to an official income declaration.
Mr Peskov said his 36.7m rouble (£383,000; $544,000) income in 2015 “was salary – and sadly I got an inheritance when my father died”.
Mr Putin’s income was put as 8.9m roubles – slightly more than in 2014.
Western analysts believe Mr Putin has amassed a huge secret fortune.
In a BBC Panorama interview in January US Treasury official Adam Szubin said Mr Putin’s declaration “is not an accurate statement of the man’s wealth, and he has long time training and practices in terms of how to mask his actual wealth”.
Mr Peskov later hit back, calling the allegations a “total fabrication”.
In the Panama Papers revelations this month, it emerged that members of Mr Putin’s elite circle had channelled millions of dollars through offshore accounts. Among them was cellist Sergei Roldugin, one of Mr Putin’s closest friends.
Mr Putin has denied “any element of corruption” over the offshore schemes, saying his opponents are trying to destabilise Russia.
Wealthy gold medallist
In his declaration published last week (in Russian) Mr Putin said he owned three Russian-made cars, a trailer, a plot of land measuring 1,500 sq m (16,146 sq ft), a flat of 77 sq m and a garage.
That was dwarfed by the wealth declared by Mr Peskov and his wife Tatyana Navka, a champion ice dancer, who declared income of 89m roubles (£930,000; $1.3m) – nearly three times what Mr Peskov earned.
Ms Navka also owns two plots of land, a house, four flats – including one in the US – and a garage. She also owns two Mercedes-Benz luxury cars, a Lexus car and a quad bike. She won an Olympic gold medal as an ice dancer with Roman Kostomarov in 2006.
Mr Peskov has three flats of his own and a Toyota Land Cruiser. Their children also have their own properties.
At his wedding last year Mr Peskov was photographed wearing a Richard Mille watch worth $620,000.
Mr Peskov made a rare confession last week, saying he had wrongly informed Mr Putin that Germany’s Sueddeutsche Zeitung – the paper that revealed the Panama Papers – was owned by US bank Goldman Sachs.
When asked about Mr Putin’s reaction, Mr Peskov said “I got it in the neck” – but did not specify the punishment.
Top of the list for income in the Kremlin administration was Mr Putin’s deputy chief of staff, Vyacheslav Volodin, who declared earnings of 87.1m roubles.
In the Russian cabinet the highest income was that of Mikhail Abyzov, minister without portfolio, with 455.5m roubles.