If you were supposed to file tax returns for the four years prior to filing your Chapter 13 bankruptcy, you must have them filed by the time of your meeting of creditors (also known as the 341 meeting).
Federal Bankruptcy Procedure Rule Section 1308(a) states:
Not later than the day before the date on which the meeting of the creditors is first scheduled to be held under section 341(a), if the debtor was required to file a tax return under applicable nonbankruptcy law, the debtor shall file with appropriate tax authorities all tax returns for all taxable periods ending during the 4-year period ending on the date of the filing of the petition.