be unfront..and settle this matter.
I am not sure if IRS can provide tax details to another organization without our consent. That is why USCIS request documents from applicants rather than
directly go to other origanization. Either they can not do it or the cost of doing it is too great.
WBH,
You are misinformed and let me help you out.

Please read the fine print of all immigration applications, you grant them full consent to conduct investigation for the purposes of adjudicating you application. In the US govt eyes, this extend to each and every agency that they need to consult to make a decision your case. You sense of privacy on these issues is almost non-existent because how can they adjudicate your petition without having proper authority to do a thorough investigation? Has the FBI ever called you to request a permission to investigate your during background check?

At all times, you clear the investigation without lifting a finger to grant permission. When USCIS asks you tax related information, they can just request your information from IRS, especially when you owe taxes and this was uncovered during routine investigation, just to see if you are a liar and to have grounds to deny citizenship.
To the OP, just be upfront and if means taking a loan to settle your taxes, so let it be. However, as a person who cares about each and every person on this discussion board, especially people with legitimate cases, just be upfront because it will help your cause more than damage it. For example, let say that you pay your taxes on Sept 1, 2009 and you interview is Sept 15, 20009The fact of the matter is that you don't owe any taxes, regardless of negative impression the IO might have about your case, but the objective fact is that you don't owe taxes. The law is simple, do you own the taxes or not? If you paid them yesterday and you are asked today, you don't. Taxes are required for all N400 applications, because taxes and death are the only certainties in this world.. Good luck...