If I get a loan from a different tax service do I have to file with them and they only put one kid down for my child tax credit they messed up what do I do

[rjs]

You have to ask the other tax service what the terms of their loan are. There are no universal rules.

[Hal_Al]

You said "they only put one kid down for my child tax credit".

What makes you think you can/should claim more than one.  Claiming children, in some situations can be complicated.  There are special rules in divorce/separation (including never married), unmarried  parents living together and other relatives in the household situations. 

If they "messed up",  go back to them and straighten it out before they actually file your return.