Innocent spouse relief, which has been available under IRC § 6015 since 1998 (and was available prior to that, in a more limited way, under IRC § 6015(e)), provides three avenues of relief. Section 6015(b) provides “traditional” relief for deficiencies.
Section 6015(c) also provides relief for deficiencies for certain spouses who are divorced, separated, widowed, or not living together, by allocating the liability between the spouses. Section 6015(f) provides “equitable” relief from both deficiencies and underpayments, but only applies if a taxpayer is not eligible for relief under IRC § 6015(b) or (c).
As I reported in my 2001 Annual Report to Congress, the IRS received 46,619 claims for innocent spouse relief in fiscal year (FY) 1999 (i.e., from October 1, 1998, to September 30, 1999). The IRS received 54,402 claims for relief in FY 2000.