26 CFR §1.6015-8

1. (a)In general. Section 6015 applies to liabilities that arise after July 22, 1998, and to liabilities that arose prior to July 22, 1998, that were not paid on or before July 22, 1998.
2. (b)Liabilities paid on or before July 22, 1998. A requesting spouse seeking relief from joint and several liability for amounts paid on or before July 22, 1998, must request relief under section 6013(e) and the regulations thereunder.
3. (c)Examples. The following examples illustrate the rules of this section: