If I file married but separate I don't have to worry about losing my refund to my husband's back support will I?

[PatriciaR]

That is correct!  Your tax refund will not be offset for your husband's debt when you file Married, Filing Separately.  

However, if  you were to file Married, Filing Jointly you could prepare Form 8379 Injured Spouse Allocation to receive your portion of the refund.  

Generally, filing jointly will give you a bigger refund or less taxes due.  When you file separately, your tax rate is higher and there are several credits you cannot claim.  Please see the TurboTax FAQ below for more details:

https://ttlc.intuit.com/replies/3288477

Form 8379 Injured Spouse Allocation FAQ:

https://ttlc.intuit.com/replies/3326788