I'll try to keep this straightforward. I had entered 5 W2s for myself and wife (married, filing jointly) and TT showed refund due of $2300. After I entered another employer (wife's), it changed to tax owed of $5100, a roughly $7400 jump from refund to owed. There's nothing odd about the last W2 entered, and it did not bump us from one bracket to another, as far as my calculations tell me. The only big difference is about $22000 of employer paid health care in the last W2. Her withholding is a little lower than some of the others, but not by that much. Any idea what could cause such a huge jump?
check the entries for the w-2 especially wages box 1 and withholding box 2. Additional income can substantially affect many other items in your return. The best you can do is look at the return line by line before and after the entry to see what's changing.