I just graduated in May and for the last few months have been working part-time at two locations that do take taxes out of my paycheck, as well as a separate location where I am working as an independent contractor. Several questions when it comes to quarterly estimates...

1) Do I only pay on the income that has not already been taxed, or do I include all income up to this point?

2) I am married and we have filed jointly in the past. Do I include his income in these estimates?

I already met with a tax professional and the estimates he gave me seemed very high (to the point where working as an IC doesn't seem to make sense). Please help!