Income Splitting — Quociente Conjugal

Income splitting (quociente conjugal) is the tax calculation method applied when married couples or civil partners elect joint filing (agregação familiar). The combined household income is divided by 2, the IRS is computed on this half-income, and the result is multiplied by 2. This effectively reduces the marginal bracket rate when one spouse earns significantly more than the other — the higher earner's income is partially shifted into a lower bracket via the division. Joint filing also doubles deduction caps (health, education, PPR, etc.). The benefit of income splitting decreases as the income gap between spouses narrows — at equal incomes, separate filing and joint filing produce the same result.