3,636. Taking Challah From Starter Dough
Hilchos Bikkurim 6:19
If a baker makes a dough to be leavening and to divide, he must take challah. This is because if it doesn’t sell, he will use it as bread. However, if one makes a dough to divide as dough (i.e., into smaller loaves), he need not take challah.
Hilchos Bikkurim 6:20
Let’s say that women give a baker flour to make leavening. If none of them gave enough flour to make a dough that requires challah, then even though the dough made from all their flour combined is large enough to require challah, it need not be taken