Nigeria's government plans to write to 500 wealthy Nigerians with property and trusts abroad, urging them to come clean about their tax status or risk being being prosecuted and fined.
In a statement, the finance ministry said it had come across cases where people declared as little as 10 million naira ($28,000; £21,000) as income, but purchased expensive property in Nigeria and overseas, owned "high specification vehicles" and funded luxurious events.
It urged Nigerians should take advantage of a tax amnesty, which expires in March, to regularise their tax affairs.
The statement added:
The first 500 letters are ready and will go out this week but there are many more. Receiving the letter is not an accusation of deliberate wrongdoing, rather a notice that the data suggests possible underpayment and a prompt to check compliance."
The moves comes as the government plans to to impose special taxes on luxury cars, cigarettes and alcohol in a bid to cushion the deficit in the 2018 budget of 8.6 trillion naira (£21.4bn).
The budget, unveiled on 7 November, aims to help the economy recover from its first recession in 25 years.
The government hopes to raise 60bn naira from duties on cigarettes and alcohol and about 2.5bn from “special taxes” on luxury cars, the local Punch newspaper