My reports were looking odd, especially the amount of social security tax paid each year, until I realized that I'd changed my salary in the Earnings tab, but it hadn't been updated in the Social Security / Future Covered Earnings tab. The Future Earnings tab has a "copy" button, but that's easy to forget when the salary editing is being done elsewhere.

As a UX professional, some suggestions for preventing problems like this in the future
- Tie the two together so they can't get out of sync, possibly with a checkbox asking me if I want them tied or not, or by having me enter salary already segregated into salary that has social security taxes and salary that doesn't. This is probably the most work for the developers.
- Add an equivalent of the "copy" button currently on the "Future covered earnings" tab to the "Employee Wages" tab.
- Add a check somewhere that lets you know if those two salary lists are different. Helpful if you always want them the same, but could be annoying if you have a good reason for leaving them different (I'm not sure how common a use case that is).