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15. INCOME TAX AND SOCIAL CONTRIBUTION (Details 3) | 12 Months Ended
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Dec. 31, 2018
Tax losses |
Disclosure of fair value measurement of liabilities [line items] |
Description of deferred tax assets on tax losses and temporary differences | In recent periods, the Company started to incur in tax losses, mostly because of high financial expenses, as substantially all our loans and financings of CSN group, and presented a taxable income in 2018.
Foreign exchange differences |
Disclosure of fair value measurement of liabilities [line items] |
Description of deferred tax assets on tax losses and temporary differences | Since 2012 the Company opted by the taxation of exchange differences on a cash basis. As the Company have operated without taxable profit it would not make sense to use this deductibility year by year (accrual basis). As a result of the cash basis tax treatment, taxes are only due and expenses are only deductible at the time of debt settlement.
Losses on Usiminas shares |
Disclosure of fair value measurement of liabilities [line items] |
Description of deferred tax assets on tax losses and temporary differences | The losses on Usiminas shares are recognized on an accrual basis, but the taxable event will occur only at the time of divestment.
Other provisions |
Disclosure of fair value measurement of liabilities [line items] |
Description of deferred tax assets on tax losses and temporary differences | Various accounting provisions are recognized on an accrual basis, but their taxation occurs only at the time of its realization, such as provisions for contingencies, impairment losses, environmental liabilities, etc.

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