Russia plans a new tax on exporters to soak up excess revenue companies reap when the ruble depreciates past a certain level and support its strained wartime budget. 

The Finance Ministry is proposing a levy on exporters that kicks in once the ruble weakens past 80 per US dollar, four people familiar with situation said, declining to be identified as the decision isn’t final. Oil, gas, grain and some other goods would be excluded under the plan, leaving industries like metal and mining to shoulder the biggest burden.

The ruble is the third-worst performing currency this year in emerging markets after briefly depreciating past 100 per dollar in August. A weaker domestic currency can boost revenue from exports in ruble terms. The new tax would help funnel some of that windfall toward the budget, which remains under pressure from the financial drain of the war in Ukraine. The ruble traded at 96.3 per dollar at 10:57 a.m. in Moscow.

The tax is expected to generate about $1 billion per month at the current exchange rate, said one of the people, who is close to the government.

The government and Finance Ministry’s press services didn’t respond to requests for comment. 

The new tax was discussed on Sept. 18 by a government commission responsible for tariffs and met no objections, according to Kommersant newspaper, which earlier reported the levy was being considered. The tax may be implemented as soon as the fourth quarter. 

Should the proposal pass, the scale would be progressive, with exporters paying as much as 4% on revenue when the ruble is weaker than 80 per dollar and 7% when it depreciates past 95 per dollar, people said. 

The ruble’s August fall triggered a spat between the government and the central bank over whether to introduce capital controls. 

While the central bank thinks that hiking its key interest rate is enough to protect the currency and make ruble assets more appealing, the Finance Ministry is arguing for tighter restrictions on the movement of capital. 

In the wake of Russia’s invasion of Ukraine, the government required mandatory foreign exchange sales by exporters, and those companies think the new tax could be a milder form capital control for now, people said. 

Russian fertilizers and most metals, including nickel, palladium and aluminum, aren’t sanctioned, partially due to their importance for global trade. Some of these exporters are seeing revenues skyrocket, even as they encounter some international clients reluctant to purchase Russian goods. 

Many of the companies have trading units overseas in places like Switzerland and Dubai, making it difficult for Russia to track how much currency they keep in international accounts.