MOSCOW, Aug 31 (Reuters) - Russia's No. 2 lender VTB still expects to earn 400 billion roubles ($4.21 billion) this year but this month's big central bank rate hike has trimmed any upside to that guidance, Chief Financial Officer Dmitry Pyanov said.

The state-controlled bank said last month its 2023 net profit could come in excess of 400 billion roubles.

Pyanov said VTB had made a net profit of 325.4 billion roubles in January-July under International Financial Reporting Standards, including 35.6 billion in July alone. VTB did not disclose its earnings for the same period of 2022.

"If we previously assumed in our communications that we could exceed 400 billion roubles as a target for net profit, then naturally this positive upside over 400 billion was slightly curtailed by the decision of the central bank," he said.

The Bank of Russia jacked up its key rate to 12% on Aug. 15 in an emergency move to try and halt the rouble's recent slide past 100 to the dollar.

"In August there will still be a minor impact (from the rate hike), but we expect that from September the underlying profit of the VTB Group ... will be 20+ billion roubles per month rather than 30+ billion," Pyanov said.

The rate hike also means the lender will fall short of its full-year loan portfolio growth forecast, he added. It is expected to shave 1 percentage point off its total lending growth, and 2 percentage points off corporate loan portfolio growth.

Volatility on the foreign exchange market in August has so far had zero impact on VTB results because the lender had significantly cut its net forex position, Pyanov said.

He also said VTB was not subject to the windfall profit tax that Russia is levying on companies' excess profits because it made a loss last year. Rival lender Sberbank said last week it would pay 3 billion roubles to the state budget.

($1 = 95.1000 roubles) (Reporting by Elena Fabrichnaya; writing by Maria Kiselyova; Editing by Mark Trevelyan)