Medicare has a flat tax rate of 2.9%. Half is paid by your employer. The other half is paid by you.
This tax pays for your hospital insurance when you turn 65. It also covers hospital stays, skilled nursing facilities, and some health care services.
Social Security is a flat tax rate of 12.4%. Half is paid by your employer. The other half is paid by you. This provides your Social Security Benefit in addition to any IRA’s or pensions you may have when you retire.
The beauty of the flat tax rate is that it is predictable. What is not predictable are your Federal Taxes. Your Federal Tax Rate has so many contributing factors to it that it can be a small exercise to get it right and it can be a source of frustration when you get it wrong.
On top of that we have a progressive tax system that can also be a challenge to factor. Add to the fact that you may have more than one job. Your HR department is only withholding based on what you earn with the company. It cannot factor in what you are earning from your other jobs. Your Tax Preparer is one of your best resources to help you utilize the worksheet on the W-4.