I'm sorry, but this was your OWN paycheck. You mean you don't check you own paycheck? It's pretty obvious when you're supposed to have a deduction and the amount is paid instead.

I find it very hard to believe you didn't know. When you try something for the first time, you check the results immediately. I've been in payroll for over 30 years and honestly, I don't believe you when you say you didn't know there was an error. Even if it was a simple mistake, that's why you check your work. If you don't check your work and you make continuing errors on YOUR paycheck for multiple paychecks in a row, you weren't doing your job adequately and you cost the company money to YOUR advantage.

It's very simple to check your own paycheck.