Can 2005 tax payment be deducted/reduced from 2006 gross income?

My new spouse had a huge amount to pay for her taxes from 2005 because he defaulted on a 401k loan; we are working towards getting the money back from him, which will happen over time, but my question is whether this exorbitant amount she had to pay is available to be deducted from gross income in 2006 or if there's any type of credit for this? HELP!