Chapter 13 of the Bankruptcy Code provides bankruptcy protection to ‘‘individual[s] with regular income’’ whose debts fall within statutory limits. [Citation.] Unlike debtors who file under Chapter 7 and must liquidate their nonexempt assets in order to pay creditors, [citation], Chapter 13 debtors are permitted to keep their property, but they must agree to a court-approved plan under which they pay creditors out of their future income, [citation]. A bankruptcy trustee oversees the filing and execution of a Chapter 13 debtor’s plan. [Citations.]

   Section 1325 of the [Bankruptcy Code] specifies circumstances under which a bankruptcy court ‘‘shall’’ and ‘‘may not’’ confirm a plan. §1325(a), (b). If an unsecured creditor or the bankruptcy trustee objects to confirmation, §1325(b)(1) requires the debtor either to pay unsecured creditors in full or to pay all ‘‘projected disposable income’’ to be received by the debtor over the duration of the plan.

   We granted certiorari to decide how a bankruptcy court should calculate a debtor’s ‘‘projected disposable income.’’ Some lower courts have taken what the parties term the ‘‘mechanical approach,’’ while most have adopted what has been called the ‘‘forward-looking approach.’’ We hold that the ‘‘forward-looking approach’’ is correct.

I

* * * Before the enactment of the Bankruptcy Abuse Prevention and Consumer Protection Act of 2005 (BAPCPA), [citation], the Bankruptcy Code (Code) loosely defined ‘‘disposable income’’ as ‘‘income which is received by the debtor and which is not reasonably necessary to be expended’’ for the ‘‘maintenance or support of the debtor,’’ for qualifying charitable contributions, or for business expenditures. §1325(b)(2)(A), (B).

   The Code did not define the term ‘‘projected disposable income,’’ and in most cases, bankruptcy courts used a mechanical approach in calculating projected disposable income. That is, they first multiplied monthly income by the number of months in the plan and then determined what portion of the result was ‘‘excess’’ or ‘‘disposable.’’ [Citation.]

   In exceptional cases, however, bankruptcy courts took into account foreseeable changes in a debtor’s income or expenses. [Citations.]

   BAPCPA left the term ‘‘projected disposable income’’ undefined but specified in some detail how ‘‘disposable income’’ is to be calculated. ‘‘Disposable income’’ is now defined as ‘‘current monthly income received by the debtor’’ less ‘‘amounts reasonably necessary to be expended’’ for the debtor’s maintenance and support, for qualifying charitable contributions, and for business expenditures. [Citation.] ‘‘Current monthly income,’’ in turn, is calculated by averaging the debtor’s monthly income during what the parties refer to as the 6-month look-back period, which generally consists of the six full months preceding the filing of the bankruptcy petition. [Citation.] The phrase ‘‘amounts reasonably necessary to be expended’’ in §1325(b)(2) is also newly defined. For a debtor whose income is below the median for his or her State, the phrase includes the full amount needed for ‘‘maintenance or support,’’ [citation], but for a debtor with income that exceeds the state median, only certain specified expenses are included, [citations.]

II
A 

   Respondent had $36,793.36 in unsecured debt when she filed for Chapter 13 bankruptcy protection in October 2006. In the six months before her filing, she received a one-time buyout from her former employer, and this payment greatly inflated her gross income for April 2006 (to $11,990.03) and for May 2006 (to $15,356.42). [Citation.] As a result of these payments, respondent’s current monthly income, as averaged from April through October 2006, was $5,343.70—a figure that exceeds the median income for a family of one in Kansas. [Citation.] Respondent’s monthly expenses, calculated pursuant to [citation] were $4,228.71. [Citation.] She reported a monthly ‘‘disposable income’’ of $1,114.98 on Form 22C. [Citation.]

   On the form used for reporting monthly income (Schedule I), she reported income from her new job of $1,922 per month—which is below the state median. [Citations.] On the form used for reporting monthly expenses (Schedule J), she reported actual monthly expenses of $1,772.97. [Citation.] Subtracting the Schedule J figure from the Schedule I figure resulted in monthly disposable income of $149.03.

   Respondent filed a plan that would have required her to pay $144 per month for 36 months. [Citation.] 814 Part 8 Debtor and Creditor Relations Petitioner, a private Chapter 13 trustee, objected to confirmation of the plan because the amount respondent proposed to pay was less than the full amount of the claims against her, [citation], and because, in petitioner’s view, respondent was not committing all of her ‘‘projected disposable income’’ to the repayment of creditors, [citation]. According to petitioner, the proper way to calculate projected disposable income was simply to multiply disposable income, as calculated on Form 22C, by the number of months in the commitment period. Employing this mechanical approach, petitioner calculated that creditors would be paid in full if respondent made monthly payments of $756 for a period of 60 months. [Citation.] There is no dispute that respondent’s actual income was insufficient to make payments in that amount. [Citation.]

B

   The Bankruptcy Court endorsed respondent’s proposed monthly payment of $144 but required a 60-month plan period. [Citation.] The court agreed with the majority view that the word ‘‘projected’’ in §1325(b)(1)(B) requires courts ‘‘to consider at confirmation the debtor’s actual income as it was reported on Schedule I.’’ [Citation] (emphasis added [by court]). This conclusion was warranted by the text of §1325(b)(1), the Bankruptcy Court reasoned, and was necessary to avoid the absurd result of denying bankruptcy protection to individuals with deteriorating finances in the six months before filing. [Citation.]

   Petitioner appealed to the Tenth Circuit Bankruptcy Appellate Panel, which affirmed. [Citation.] * * *

   The Tenth Circuit affirmed. * * *

   This petition followed, and we granted certiorari. [Citation.]

III
 A 

   The parties differ sharply in their interpretation of §1325’s reference to ‘‘projected disposable income.’’ Petitioner, advocating the mechanical approach, contends that ‘‘projected disposable income’’ means past average monthly disposable income multiplied by the number of months in a debtor’s plan. Respondent, who favors the forward-looking approach, agrees that the method outlined by petitioner should be determinative in most cases, but she argues that in exceptional cases, where significant changes in a debtor’s financial circumstances are known or virtually certain, a bankruptcy court has discretion to make an appropriate adjustment. Respondent has the stronger argument.

   First, respondent’s argument is supported by the ordinary meaning of the term ‘‘projected.’’ ‘‘When terms used in a statute are undefined, we give them their ordinary meaning.’’ [Citation.] Here, the term ‘‘projected’’ is not defined, and in ordinary usage future occurrences are not ‘‘projected’’ based on the assumption that the past will necessarily repeat itself. For example, projections concerning a company’s future sales or the future cash flow from a license take into account anticipated events that may change past trends. * * * While a projection takes past events into account, adjustments are often made based on other factors that may affect the final outcome. [Citation.]

   Second, the word ‘‘projected’’ appears in many federal statutes, yet Congress rarely has used it to mean simple multiplication. * * *

   By contrast, we need look no further than the Bankruptcy Code to see that when Congress wishes to mandate simple multiplication, it does so unambiguously-most commonly by using the term ‘‘multiplied.’’ [Citations.]

   Third, pre-BAPCPA case law points in favor of the ‘‘forward-looking’’ approach. Prior to BAPCPA, the general rule was that courts would multiply a debtor’s current monthly income by the number of months in the commitment period as the first step in determining projected disposable income. [Citations.] But courts also had discretion to account for known or virtually certain changes in the debtor’s income. * * * Indeed, petitioner concedes that courts possessed this discretion prior to BAPCPA. [Citation.]

   Pre-BAPCPA bankruptcy practice is telling because we ‘‘ ‘will not read the Bankruptcy Code to erode past bankruptcy practice absent a clear indication that Congress intended such a departure.’ ’’ [Citation.] Congress did not amend the term ‘‘projected disposable income’’ in 2005, and pre-BAPCPA bankruptcy practice reflected a widely acknowledged and well-documented view that courts may take into account known or virtually certain changes to debtors’ income or expenses when projecting disposable income. In light of this historical practice, we would expect that, had Congress intended for ‘‘projected’’ to carry a specialized—and indeed, unusual— meaning in Chapter 13, Congress would have said so expressly. [Citation.]

B

   The mechanical approach also clashes repeatedly with the terms of 11 U.S.C. §1325.

   First, §1325(b)(1)(B)’s reference to projected disposable income ‘‘to be received in the applicable commitment period’’ strongly favors the forward-looking approach. There is no dispute that respondent would in fact receive far less than $756 per month in disposable income during the plan period, so petitioner’s projection does not accurately reflect ‘‘income to be received’’ during that period. [Citation.] The mechanical approach effectively reads this phrase out of the statute when a debtor’s current disposable income is substantially higher than the income that the debtor predictably will receive during the plan period. [Citation.]

   Second, §1325(b)(1) directs courts to determine projected disposable income ‘‘as of the effective date of the plan,’’ which is the date on which the plan is confirmed and becomes binding, see §1327(a). Had Congress intended for projected disposable income to be nothing more than a multiple of disposable income in all cases, we see no reason why Congress would not have required courts to determine that value as of the filing date of the plan. [Citation.] * * * Congress’ decision to require courts to measure projected disposable income ‘‘as of the effective date of the plan’’ is more consistent with the view that Congress expected courts to consider post-filing information about the debtor’s financial circumstances. [Citation.]

   Third, the requirement that projected disposable income ‘‘will be applied to make payments’’ is most naturally read to contemplate that the debtor will actually pay creditors in the calculated monthly amounts. §1325(b)(1)(B). But when, as of the effective date of a plan, the debtor lacks the means to do so, this language is rendered a hollow command.

C 

   The arguments advanced in favor of the mechanical approach are unpersuasive. Noting that the Code now provides a detailed and precise definition of ‘‘disposable income,’’ proponents of the mechanical approach maintain that any departure from this method leaves that definition ‘‘ ‘with no apparent purpose.’ ’’ [Citation.] This argument overlooks the important role that the statutory formula for calculating ‘‘disposable income’’ plays under the forward-looking approach. * * *

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  D

In cases in which a debtor’s disposable income during the 6-month look-back period is either substantially lower or higher than the debtor’s disposable income during the plan period, the mechanical approach would produce senseless results that we do not think Congress intended. In cases in which the debtor’s disposable income is higher during the plan period, the mechanical approach would deny creditors payments that the debtor could easily make. And where, as in the present case, the debtor’s disposable income during the plan period is substantially lower, the mechanical approach would deny the protection of Chapter 13 to debtors who meet the chapter’s main eligibility requirements. Here, for example, respondent is an ‘‘individual whose income is sufficiently stable and regular’’ to allow her ‘‘to make payments under a plan,’’ §101(30), and her debts fall below the limits set out in §109(e). But if the mechanical approach were used, she could not file a confirmable plan. Under §1325(a)(6), a plan cannot be confirmed unless ‘‘the debtor will be able to make all payments under the plan and comply with the plan.’’ And as petitioner concedes, respondent could not possibly make the payments that the mechanical approach prescribes. 

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 IV

   * * * Consistent with the text of §1325 and pre-BAPCPA practice, we hold that when a bankruptcy court calculates a debtor’s projected disposable income, the court may account for changes in the debtor’s income or expenses that are known or virtually certain at the time of confirmation. We therefore affirm the decision of the Court of Appeals.