is oasdi tax mandatory 
yes federal law requires that workers and employers contribute to the oasdi fund through social security taxation on income of up to 160 200 for 2023 and 168 600 in 2024 19at what age are social security payments no longer taxed a portion of your social security benefits is taxable regardless of your age unless your income is very low only individuals with incomes below 25 000 a year or couples with incomes below 32 000 a year keep their social security tax free everyone else pays taxes on up to 85 of their benefits depending on income 21