After you file

Thanks, wondering if say you owed 4k tax 1k federal and 3k SE tax...etc

 

and you didn't make estimated payments, what would approx be the penalty?  my mind can't seem to find any info to calculate except 365 and 4% and on and on 

 

And if estimated payments aren't made, it is just that amount at the end of the year etc during next filing or is there some additional penalty?

 

thanks!