For the vast majority of seniors, no monthly premium is paid for Medicare Part A because they or their spouse paid specialized Medicare payroll taxes for at least 40 quarters (equivalent to 10 years) of employment. For individuals who have fewer than 40 work quarters, Part A is not entirely free; those with 30 to 39 work credits pay a reduced monthly premium, while those with fewer than 30 work credits pay the full unearned premium amount, funded directly by the individual or supplementary state assistance if eligible.