Work out calories

MRC77

Ok, I am confused.... I keep reading that if you are working out you should always eat those calories back. I always thought that the point was to stay under calories. My daily calorie goal is 1600 according to MFP and then when I work out I get anywhere between 2500 and 3000 for the day. So should I eat 2500 to 3000 daily? And then also what is the "net calories" I also see?