Tax officer in TVi office
TVi interrupted its usual programming to show tax inspectors browsing through heaps of financial documents in its Kiev office.
The State Tax Service said it had launched a criminal case against TVi's chief executive, Mykola Knyazhitsky, after finding out that the station had evaded more than 3 million hryvnias ($375,000) in VAT payments, the Interfax news agency reported.
TVi has challenged the back tax claim in court, Interfax said.
Batkivshchyna, the main opposition party, accused the government of censorship.
"Batkivshchyna view this cynical move by the authorities as yet another attempt to limit freedom of speech in the country and introduce political censorship at the television station under the cover of a criminal case," it said in a statement.
Opinion polls show that Batkivshchyna, led by jailed former prime minister Yulia Tymoshenko, is close behind President Viktor Yanukovich's Party of the Regions in the run-up to the October elections.
TVi's management has said the station is owned by Konstantin Kagalovsky, a former shareholder of now-defunct Russian oil giant Yukos.