50% of the total? The US military currently accounts costs less than 9% of all taxes collected annually.
They're collected separately (and they're also really badly designed, but whatever).
So I rather us look at the amount we're spending on stuff that doesn't get a different line item on our paychecks.
Social Security, Medicare, Medicaid, and Income Security are better thought of as insurance and pension systems that happen to be run by the government. This is why they're ear-marked in federal budgets and listed separately on your paycheck.