Article 69 establishes the general rule for utilizing business losses. A taxpayer who incurs a loss in any tax year may carry that loss forward to the following year and deduct it from the taxable income of that and subsequent years until the loss is fully set off. In cases where losses are incurred over multiple years, they must be deducted in chronological order, starting with the earliest year's loss. This provision allows businesses to smooth their tax liability over time, recognizing that losses are an inherent part of commercial activity.