Can you please help me. I've showed my working but I believe something is incorrect. :confused:

Prior to the last weekly payroll period of the calendar year, the cumulative earnings of employees A and B are $99,350 and $91,000 respectively. Their earnings for the last completed payroll period of the year are $850 each. The amount of earning subject to social security tax at 6% is $100,000. All earnings are subject to Medicare tax of 1.5%. Assuming that the payroll will be paid on December 29, what will be the employer’s total FICA tax for this payroll period on the two salary amounts of $850 each?

My Working:
.06 * 850 = $51.00
.015 * 850 = 12.75 = 63.75 x 2 = $127.50

If the 6% SS tax is only subject to the first $100,000 then wouldn't only $650 of person A's check be taxable by that tax. If he accepts the $850 it puts him at $102,000, and no longer subject to the 6% tax, or does it go into a different bracket. Either way, the $100,000 mark is where you're getting things mixed up.

So what must I do, I don't understand.

Person A
$100,000 is the limit for Social Security Tax
$99,350 + $850 = $100,200
Thus $200 of this person's check is non-SS-taxable.
$850-$200 = $650
$650 * 6% = $39
The entire check is taxable by Medicare standards...
thus
$850*1.5% = $12.75
$39 + $12.75 = $51.75
...
Person B
His pay ytd plus the current pay is still under $100,000. This means that his entire check is taxable by both SS and Medicare.

Thank you a lot.