OPINION OF THE COURT
Ciparick, J.On this appeal, we are asked to interpret the Rent Stabilization Law to ascertain the consequences on a current rent overcharge claim of two rent reduction orders issued prior to, but in effect during, the four-year period preceding the filing of an overcharge claim. We conclude that the Division of Housing and Community Renewal (DHCR) should, in calculating any rent overcharge, honor rent reduction orders that, while issued prior to the four-year limitations period, remained in effect during that period.
I.
In 1986, petitioner Oscar Cintron became a tenant of 2975 Decatur Avenue, apartment 5C, in the Bronx, at an initial stabilized rent of $348.91 per month. The following year, petitioner filed a complaint with DHCR against the building’s then owner, alleging a decrease in services related to, among other things, the apartment’s refrigerator, door lock and fire escape window. As a result of the complaint, DHCR issued an order reducing petitioner’s rent “by the percentage of the most recent guidelines adjustment for the tenant’s lease which commenced before the effective date of th[e] rent reduction [order],” and providing that the owner could not collect any rent *352increase until a rent restoration order was issued. The rent reduction order did not set a particular level of rent. According to petitioner, the 1987 rent reduction order should have resulted in a reduction of his rent to $326.23 per month.
In 1989, petitioner filed another complaint with DHCR, alleging a roach infestation of the apartment’s stove. DHCR issued another rent reduction order. Despite the 1987 and 1989 rent reduction orders, however, the owner failed to make any repairs and continued to charge petitioner the unreduced rent.
In 1991, when the current owner purchased the building, petitioner allegedly advised him of the rent reduction orders. Although the current owner apparently also failed to make any repairs, petitioner continued to pay the unreduced rent and entered into a series of leases requiring him to pay greater rents.
On December 11, 2003, petitioner filed a complaint alleging that the rent of $579.99 charged in the lease then in effect constituted an overcharge based on the current and prior owners’ failure to comply with the 1987 and 1989 rent reduction orders. A DHCR Rent Administrator determined that the base date to be used was the date four years prior to the filing of the overcharge complaint—December 11, 1999—and established that the legal regulated rent on the base date was $508.99, which was the rent charged by the current owner and paid by petitioner on that date. Although taking notice of the 1987 and 1989 rent reduction orders, the Rent Administrator in establishing the legal stabilized rent calculated the overcharge using the base date of December 11, 1999. The Rent Administrator awarded petitioner a rent refund of $1,008.77, which included interest but did not include treble damages, and prospectively froze the rent at the base date level from December 11, 1999 until February 1, 2004. Effective February 1, 2004, the Rent Administrator removed the 1987 and 1989 rent reduction orders and restored the rent to the full amount of $579.99, which included rent increases.
Petitioner sought administrative review of the Rent Administrator’s order. DHCR granted the petition for administrative review to the extent of modifying the order by (1) reversing the portion of the order that denied treble damages and (2) awarding treble damages beginning two years prior to the filing of the overcharge complaint. DHCR denied the remainder of petitioner’s challenges, concluding that the Rent Administrator properly limited recovery to the four years preceding the overcharge *353complaint and correctly used the base date rent—$508.99 as of December 11, 1999—rather than the rent established by the 1987 and 1989 rent reduction orders in calculating the overcharge.
Petitioner commenced this CPLR article 78 proceeding seeking to annul DHCR’s order. Supreme Court denied the petition and dismissed the proceeding, concluding that DHCR’s determination was not arbitrary or capricious and had a rational basis.
On petitioner’s appeal, the Appellate Division affirmed, holding:
“The order, finding the base rent date to be December 11, 1999 (four years prior to the filing of the overcharge complaint), establishing the legal base rent as the amount paid on that date, freezing that rent until February 1, 2004, during which time rent reduction orders were extant, and directing the owner to refund overcharges collected from the base rent date inclusive of treble damages, was not arbitrary and capricious, and had a rational basis” (Matter of Cintron v Calogero, 59 AD3d 345, 346 [1st Dept 2009] [citations omitted]).1
Petitioner appealed to this Court by permission of the Appellate Division, which certified the following question: “Was the order of this Court, which affirmed the order of the Supreme Court, properly made?” Because the Appellate Division order is final, we need not answer the certified question.
II.
Regardless of the forum in which it is commenced, a rent overcharge claim is subject to a four-year statute of limitations (see Rent Stabilization Law of 1969 [Administrative Code of City of NY] § 26-516 [a] [2] [hereinafter Rent Stabilization Law]; CPLR 213-a).2 The Rent Regulation Reform Act of 1997 “clarified and reinforced the four-year statute of limitations *354applicable to rent overcharge claims ... by limiting examination of the rental history of housing accommodations prior to the four-year period preceding the filing of an overcharge complaint” (Thornton v Baron, 5 NY3d 175, 180 [2005], citing Matter of Gilman v New York State Div. of Hous. & Community Renewal, 99 NY2d 144, 149 [2002]; see also Matter of Grimm v State of N.Y. Div. of Hous. & Community Renewal Off. of Rent Admin., 15 NY3d 358 [2010] [decided today]). Notably, the term “rental history” is not defined in the relevant statutes or in DHCR regulations and we need not attempt to define it here. As we have previously explained, the purpose of the four-year limitations or look-back period is to “alleviate the burden on honest landlords to retain rent records indefinitely” (Thornton, 5 NY3d at 181, citing Matter of Gilman, 99 NY2d at 149; see also Jenkins v Fieldbridge Assoc., LLC, 65 AD3d 169, 174 [2d Dept 2009], appeal dismissed 13 NY3d 855 [2009]).
Moreover, Rent Stabilization Law § 26-514, which addresses rent reduction orders, states:
“[A]ny tenant may apply to [DHCR] for a reduction ■ in the rent to the level in effect prior to its most recent adjustment and for an order requiring services to be maintained as provided in this section, and [DHCR] shall so reduce the rent if it is found that the owner has failed to maintain such services. The owner shall also be barred from applying for or collecting any further rent increases. The restoration of such services shall result in the prospective elimination of such sanctions” (emphasis added).
Rent reduction orders thus place a “continuing obligation” *355upon an owner to reduce rent until the required services are restored or repairs are made (Thelma Realty Co. v Harvey, 190 Misc 2d 303, 305-306 [App Term, 2d Dept 2001]; see also Matter of Condo Units v New York State Div. of Hous. & Community Renewal, 4 AD3d 424, 425 [2d Dept 2004], lv denied 5 NY3d 705 [2005]; Crimmins v Handler & Co., 249 AD2d 89, 91 [1st Dept 1998]). Here, it is alleged that the landlord failed to fulfill his continuing obligation by willfully flouting DHCR rent reduction orders.
The Rent Stabilization Law and Code are unfortunately silent as to the effect that a rent reduction order, issued prior to the four-year limitations period but still in effect during that period, as is the case here, has on a subsequent overcharge complaint based on that order. Petitioner argues that DHCR rent reduction orders must be considered by DHCR in establishing the legal stabilized rent for an apartment for the purposes of an overcharge complaint and that, because the rent reduction orders here remained in effect—and imposed a continuing duty on the landlord to reduce rent—during the relevant four-year period, the four-year look-back rule is no bar to considering those orders for the purposes of calculating the amount by which petitioner was overcharged (see Thornton, 5 NY3d at 180; see also Matter of 508 Realty Assoc., LLC v New York State Div. of Hous. & Community Renewal, 61 AD3d 753, 755-756 [2d Dept 2009]; Jenkins, 65 AD3d at 173). DHCR, on the other hand, argues that its determination is supported by a rational basis and is consistent with the statute as the Legislature intended the four-year limitations/look-back period to be absolute, prohibiting the consideration of earlier rent records for the purpose of calculating a rent overcharge.
In this matter of statutory construction, where deference to an agency’s interpretation is not required (see e.g. Roberts v Tishman Speyer Props., L.P., 13 NY3d 270, 285 [2009]), we find petitioner’s argument more persuasive as it best reconciles and harmonizes the legislative aims of both the four-year limitations/ look-back period as set forth in Rent Stabilization Law § 26-516 (a) (2) and CPLR 213-a and the “continuing obligation” of a landlord to reduce rent and make repairs as per Rent Stabilization Law § 26-514 (see McKinney’s Cons Laws of NY, Book 1, Statutes §§ 95, 96 [in interpreting statutes, the goal is to further the intent, spirit and purpose of a statute, to harmonize all parts of a statute to give effect and meaning to every part]).
Certainly, DHCR can take notice of its own orders and the rent registrations it maintains to ascertain the rent established *356by a rent reduction order without imposing onerous obligations on landlords. Moreover, refusing to give effect to a rent reduction order’s direction to roll back rent in cases where the order remained in effect during the statutory four-year period would countenance the landlord’s failure to restore required services and thwart the goals of the Legislature in enacting Rent Stabilization Law § 26-514, namely, to “motivate owners of rent-stabilized housing accommodations to provide required services, compensate tenants deprived of those services, and preserve and maintain the housing stock in New York City” (Jenkins, 65 AD3d at 173, citing Matter of Hyde Park Assoc. v Higgins, 191 AD2d 440, 442 [1st Dept 1993]). In short, rent reduction orders impose a continuing obligation on a landlord and, if still in effect during the four-year period, are in fact part of the rental history which DHCR must consider.
We conclude that the purposes of the relevant statutes are best served here if DHCR calculates the amount of rent overcharge by reference to the 1987 and 1989 rent reduction orders, which remained in effect during the four-year limitations period and, accordingly, were part of the rental history that the Rent Stabilization Law permits DHCR to consider.
Accordingly, the order of the Appellate Division should be reversed, with costs, and the case remitted to Supreme Court with directions to remand to respondent DHCR for further proceedings in accordance with this opinion. The certified question should not be answered upon the ground that it is unnecessary.
. The Appellate Division further held that “DHCR appropriately limited the amount of rent overcharges recoverable to the four years prior to the filing of the overcharge complaint” (59 AD3d at 346). This is not an issue on this appeal as petitioner has abandoned his claim for rent overcharges in excess of four years prior to the filing of his rent overcharge claim with DHCR. Petitioner is merely seeking to have the base rent date set at an earlier time.
. Rent Stabilization Law § 26-516 (a) (2) states:
“[A] complaint under this subdivision shall be filed with [DHCR] within four years of the first overcharge alleged and no determi*354nation of an overcharge and no award or calculation of an award of the amount of an overcharge may be based upon an overcharge having occurred more than four years before the complaint is filed . . . This paragraph shall preclude examination of the rental history of the housing accommodation prior to the four-year period preceding the filing of a complaint pursuant to this subdivision,”
and CPLR 213-a states:
“An action on a residential rent overcharge shall be commenced within four years of the first overcharge alleged and no determination of an overcharge and no award or calculation of an award of the amount of any overcharge may be based upon an overcharge having occurred more than four years before the action is commenced. This section shall preclude examination of the rental history of the housing accommodation prior to the four-year period immediately preceding the commencement of the action.”