<p>Social security systems in developed countries are typically the largest single item of public expenditure, and affect virtually every member of the population at some point, whether through universal benefits to children, benefits to the elderly, benefits for the unemployed or sick, or simply payments to those on low income. That the social security system should function effectively is important to current recipients, non-recipients who expect to be entitled to benefit at some time, and to those who finance social security spending through tax payments.</p>