"When a married couple opts for joint assessment, they are treated as a *single entity* for tax purposes.
This means that both their incomes are combined, and they benefit from shared tax credits and reliefs.
Filing Requirements
Form 12: This form is typically used by individuals whose main source of income is from PAYE (Pay As You Earn) employment or pensions. If both spouses have unearned income of less than €5,000 each, they can file Form 12 jointly, provided their total unearned income does not exceed €5,000.
Form 11: If their combined unearned income exceeds €5,000, they must file Form 11. This requirement holds even if each spouse's individual unearned income is below the threshold but collectively exceeds €5,000.
Form 11 is required for self-assessment and is necessary for individuals with significant non-PAYE income.
Summary of Conditions
Both Spouses Below €5,000: If each spouse has less than €5,000 in unearned income and their combined total remains below €5,000, they can use Form 12.
Combined Income Exceeds €5,000: If their combined unearned income exceeds €5,000, one or both spouses will need to register with ROS (Revenue Online Service) and complete Form 11."