Credit Agricole posted a 6.5 billion-euro ($8.68 billion) full-year loss - the worst since the French bank went public in 2001 - as taxes on the sale of its Greek unit pushed the bank even deeper into the red than expected.
Bank executives told reporters an unexpected decision by French tax authorities to disallow a tax deduction the bank was seeking for the sale of Emporiki Bank triggered an 838 million-euro tax hit, pushing fourth-quarter writedowns to 4.53 billion.
"The government told us very recently - (Monday) to tell the truth - that we could no longer deduct taxes from these losses," Chief Financial Officer Bernard Delpit said on a conference call.
The tax expense, on top of previous writedowns mostly related to the impact of a worsening economic outlook on goodwill, pushed the bank's quarterly loss to 3.982 billion euros.
(Read More: Credit Agricole Hit by 3.8 Billion Euros in Charges)
Credit Agricole said on Wednesday its "normalized" profit excluding one-off items rose 10 percent from a year ago to 548 million.
Analysts polled by Thomson Reuters I/B/E/S had forecast net income of 402 million euros on average, but it was unclear whether their forecasts stripped out the same elements as the bank's normalized figure.