Chapter 13 debtors commenced adversary proceeding against IRS, requesting declaratory judgment that tax liabilities were discharged and seeking return of sums paid to the IRS postpetition, plus attorney's fees and costs. Debtors moved for summary judgment. The court held that: (1) taxes become payable when tax return is due, not when income on which tax was applied was earned; (2) requirements for waiver of sovereign immunity were met; and (3) debtors were entitled to recover property seized postpetition, as well as attorney's fees and costs incurred in pursuing the proceeding.