Indonesia announced plans on Friday to impose a minimum tax on thousands of companies that have reported losses for years but are still operating regardless, part of a push to raise revenues that a senior official said would hit foreign firms hardest.

"Most of them operate normally without signs of bankcruptcy ... That is an insult to the tax authority," Finance Minister Bambang Brodjonegoro told Reuters, complaining that by declaring losses many companies, most of them foreign firms, avoid paying any taxes.

Goro Ekanto, head of revenue policy in the fiscal policy office, said that such companies would now face an "alternative minimum tax" (AMT) on their turnover.

Indonesia's corporate income tax rate is 25 percent of net profit. Companies that have a large chunk of shares traded in the stock market pay a lower rate of 20 percent.

Indonesia had a large tax shortfall last year when exports fell, corporate earnings dropped and economic growth slowed to 4.8 percent, its slowest pace since 2009.

Brodjonegoro has said the government could face another big fiscal shortfall this year, and the government is counting on a tax amnesty plan to narrow the gap.

However, a parliamentary debate on the tax amnesty bill has been delayed until at least April and analysts say it may take longer than that for it to be approved.

The AMT tax plan will be included in the revision of the Income Tax Law, which Ekanto said will be discussed after the amnesty bill is passed.

Bawono Kristiaji, a partner at Danny Darussalam Tax Center in Jakarta, said the government should check why companies are reporting losses before charging them a minimum tax.

"If these are multinational companies, then there are indications that they are practicing profit shifting through transfer pricing schemes," he said, referring to illegal practices of inflating costs or lowering prices when selling to affiliates abroad.

He said it is better to tackle this by strengthening anti-transfer pricing rules rather than imposing a new tax.

Ronny Bako, tax analyst from Jakarta's Universitas Pelita Harapan, said accounting firms must be held responsible if companies they audit made up "fake losses".

"In the current global background, there are a lot of companies making losses and it's not always the companies' fault," he said.

The tax office is already targeting individuals more aggressively this year, using "geo-tagging" from Internet-based maps to check on assets.

It is also imposing land tax on miners in a different way this year, by charging for mine deposits as well as the value of the land around them, local media reported.