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Open Decision Ledger · Civil obligations & remedies

Conversion price limits, partial invalidity and commercial statutory interest

Supreme Court, Aug. 27, 2020, 2016Da26198 (judgment)

No holding summary · checked against points at issue. The official text publishes no summary of the holding for this decision. The quotation and factors in this record are copied verbatim from the points at issue; the evidence for each axis is taken from the points at issue, the order and the reasons.

Case name: 부당이득금

Official text on the National Law Information Center

  1. Question

    Do the conversion-price calculation standards in Article 9(1) and Table 1 of the former Enforcement Rules of the Rental Housing Act bind a private rental operator whose conversion received the approval of the mayor, so that a sale contract concluded above the lawful amount is void in the excess, and must the court apply the commercial statutory interest rate under Article 54 of the Commercial Act to the resulting claim for restitution?

  2. Holding

    Yes. The price standards in the former Enforcement Rules of the Rental Housing Act are mandatory rules, and a sale contract concluded above the amount computed under them is void to the extent of the excess, even where a private rental operator converted the housing with the approval of the mayor, which the mayor may only check and not adjust. Because that restitution claim arose from a sale contract the defendant concluded in the course of trade and the trade relation needs a swift resolution, the commercial statutory interest rate under Article 54 of the Commercial Act applies to the delayed damages. The land cost must be found by deducting the prepayment discount from the price actually paid and adding the period interest on the prepaid money from the date of prepayment to six months after the first recruitment announcement.

    Points at issue, verbatim

    위 산정기준에 따른 금액을 초과하는 분양전환가격으로 체결된 분양계약의 효력(=초과하는 범위에서 무효) / 이러한 일부 무효의 법리는 민간 임대사업자가 시장 등의 분양전환승인을 거쳐 분양전환을 한 경우에도 마찬가지로 적용되는지 여부(적극)

    Unofficial English translation

    the effect of a sale contract concluded at a sale conversion price exceeding the amount calculated under the said calculation criteria (= void to the extent of such excess) / whether the legal principle of such partial voidness likewise applies where a private rental housing operator carries out a sale conversion after obtaining approval for the sale conversion from the mayor, etc. (affirmative)
  3. Disposition

    Reversed and remanded Stated in the decision

    원심판결을 파기하고, 사건을 서울고등법원에 환송한다.

    Unofficial English translation

    The judgment of the court below is reversed, and the case is remanded to the Seoul High Court.
  4. Form of the test

    Elements stated Stated in the decision

    구 임대주택법 시행규칙 제9조 제1항 [별표 1]에서 분양전환가격 산정의 기초가 되는 건축비는 특별한 사정이 없는 한 표준건축비의 범위 내에서 실제로 투입된 건축비를 의미한다고 보아야 한다

    Unofficial English translation

    The construction costs that serve as the basis for calculating the sale conversion price under Article 9 (1) [Table 1] of the Enforcement Rule of the former Rental Housing Act must be regarded, absent special circumstances, as meaning the construction costs actually incurred within the scope of the standard construction costs
  5. Factors

    • ‘분양전환 당시 건축비’의 의미(=분양전환 당시 표준건축비)
    • 분양전환가격 산정 기초로 정한 건축비의 의미(=표준건축비의 범위 내에서 실제로 투입된 건축비)
    • 강행법규를 위반한 자가 스스로 그 약정의 무효를 주장하는 것이 신의칙에 반하는지 여부(원칙적 소극)
    • 임대사업자가 공급받은 공공택지의 대금을 선납함으로써 대금을 일부 할인받은 경우 분양전환가격의 기초가 되는 택지비를 산정하는 방법

    Unofficial English translation

    • Meaning of the "construction costs at the time of sale conversion" (= standard construction costs at the time of sale conversion)

    • Meaning of the construction costs set forth as the basis for calculating the sale conversion price (= construction costs actually incurred within the scope of the standard construction costs)

    • Whether a person who has violated a mandatory rule asserting the invalidity of his or her own agreement contravenes the principle of good faith (in principle, negative)

    • Method of calculating the land cost serving as the basis for the sale conversion price where a rental housing operator prepaying the price of a public housing site supplied to it thereby receives a partial discount on such price

  6. Relation to precedent

    Follows earlier decisions Stated in the decision

    대법원 2011. 4. 21. 선고 2009다97079 전원합의체 판결

    Unofficial English translation

    Supreme Court en banc judgment 2009Da97079 decided April 21, 2011

    Decisions referred to

    [1] 대법원 2015. 4. 23. 선고 2013다203468 판결, 대법원 2015. 9. 15. 선고 2013다212233 판결, 대법원 2016. 12. 27. 선고 2015다51425 판결 / [2] 대법원 2016. 6. 10. 선고 2014다200763, 200770 판결(공2016하, 929) / [3][5] 대법원 2011. 4. 21. 선고 2009다97079 전원합의체 판결(공2011상, 993) / [3] 대법원 2017. 11. 9. 선고 2015다44274 판결 / [4] 대법원 2007. 11. 29. 선고 2005다64552 판결(공2007하, 2001), 대법원 2011. 3. 10. 선고 2007다17482 판결(공2011상, 699) / [5] 대법원 2015. 8. 27. 선고 2014다66727 판결 / [7] 대법원 2011. 7. 28. 선고 2010다55309 판결, 대법원 2013. 2. 14. 선고 2012다55884 판결, 대법원 2015. 9. 15. 선고 2015다210811 판결

  7. Burden of proof

    Not addressed Not in the decision

  8. Open question and revisit condition

    If the operator produces records showing costs that were left out of the acquisition tax base, how is the actual construction cost then to be found?

    A later decision on the scope of the commercial obligations governed by Article 54 of the Commercial Act, or an amendment to Article 40 and Table 7 of the Enforcement Rules of the Public Housing Special Act now cited in place of Table 1, would require this entry to be read again.

Cross-family AI independent reading & axis check

8 of 8 axes matched GPT-6 Astra (OpenAI, codex CLI) · 2026-10-25

A reader from another model family (GPT-6 Astra), given the official text but not the primary reading, agreed on all 8 axes.

Raw responses and comparison record: Protocol · Blind readings (JSONL) · Axis comparison (JSONL) · SHA-256 (JSON)

Lower-court contrast & scope of application

Lower-court reading vs. Supreme Court holding

Lower-court context: The Seoul High Court, in its judgment of 19 May 2016 (2014Na61229), computed the cap on the conversion price from the standard construction cost at the time of conversion and deducted from that amount the depreciation for the rental period, measured on the house price at the first recruitment announcement. It applied the interest rate for own funds laid down in the Rules then in force, and set the rate of delayed damages on the plaintiffs' restitution claim at the statutory rate under the Civil Act. On the land cost it deducted the discount the defendant obtained by prepaying the price of the public land, but added no period interest on the prepaid money.

Supreme Court standard: The Supreme Court found no error in the cap calculation and its depreciation base, in the interest rate for own funds, or in the holding that the price standards are mandatory rules and that the partial invalidity reaches a private operator who converted with the approval of the mayor. It also accepted the finding that the acquisition tax base the defendant reported was the actual construction cost, since the appraisal only estimated costs from the approved drawings and the defendant produced no records of costs left out of the tax base, and it accepted that the plaintiffs' claim was not barred by good faith. It held, however, that the claim arose from a sale contract concluded in the course of trade and required a swift resolution of the trade relation, so Article 54 of the Commercial Act applied, and that failing to add the period interest on the prepaid land money was a misreading of the law, and reversed the whole judgment and remanded the case to the Seoul High Court.

Distinguishing conditions

  • A conversion price that does not exceed the amount computed under the statutory standards, so that no part of the sale contract is void.
  • A rental operator that has produced records of the costs left out of the acquisition tax base, since the reported acquisition tax base was accepted as actual construction cost where nothing else was produced.
  • Land cost of private land, or of public land whose price was not prepaid, since the period interest addition addresses a prepayment discount.

Record verification notes

Set each sale contract against the amount computed under the former Enforcement Rules in force on the date of conversion, because only the excess is void. Check whether the operator is a private one that obtained the approval of the mayor under Article 21(3) and (4) of the former Rental Housing Act, and whether it produced cost records, since the reported acquisition tax base was accepted as actual construction cost where nothing else was produced. Fix the date of prepayment of the public land price and the date six months after the first recruitment announcement, because the period interest runs between those two dates.

From the official text

Points at issue

[1] 구 임대주택법 시행규칙 제9조 제1항 [별표 1]에서 분양전환가격의 상한가격 산정 기초로 정한 ‘분양전환 당시 건축비’의 의미(=분양전환 당시 표준건축비) 및 위 상한가격 산정 시 산정가격에서 공제할 ‘임대기간 중 감가상각비’는 최초 입주자 모집공고 당시 주택가격을 기준으로 산정하여야 하는지 여부(적극) [2] 상법 제54조의 상사법정이율이 적용되는 ‘상행위로 인한 채무’의 범위 [3] 분양전환가격 산정기준에 관한 구 임대주택법 등 관련 법령의 규정이 강행법규인지 여부(적극) 및 위 산정기준에 따른 금액을 초과하는 분양전환가격으로 체결된 분양계약의 효력(=초과하는 범위에서 무효) / 이러한 일부 무효의 법리는 민간 임대사업자가 시장 등의 분양전환승인을 거쳐 분양전환을 한 경우에도 마찬가지로 적용되는지 여부(적극) [4] 강행법규를 위반한 자가 스스로 그 약정의 무효를 주장하는 것이 신의칙에 반하는지 여부(원칙적 소극) 및 신의성실의 원칙에 위배된다는 이유로 권리의 행사를 부정하기 위한 요건 [5] 구 임대주택법 시행규칙 제9조 제1항 [별표 1]에서 분양전환가격 산정 기초로 정한 건축비의 의미(=표준건축비의 범위 내에서 실제로 투입된 건축비) [6] 갑 주식회사가 스스로 건설하여 을 등에게 임대하였다가 분양전환하는 임대아파트의 분양전환가격을 산정하면서 그 산정의 기초가 되는 ‘실제 건축비’를 위 아파트의 취득세 과세표준과 건축비 감정 결과 중 어느 것을 토대로 인정하여야 하는지 문제 된 사안에서, 갑 회사가 위 아파트의 취득세 과세표준으로 신고한 금액을 토대로 실제 건축비를 인정한 원심판단에 법리오해 등의 잘못이 없다고 한 사례 [7] 구 임대주택법 시행규칙 제9조 제1항 [별표 1] 제2호 (라)목 2) 가)에서 임대주택의 분양전환가격 구성요소 중 하나인 택지비의 산정기준으로 정한 ‘공급가격’의 의미 및 위 [별표 1] 제2호 (라)목 2) 다) (1)에서 선납한 택지대금에 대한 기간이자를 공공택지의 택지비에 가산할 수 있도록 규정한 취지 / 임대사업자가 공급받은 공공택지의 대금을 선납함으로써 대금을 일부 할인받은 경우 분양전환가격의 기초가 되는 택지비를 산정하는 방법

Unofficial English translation

[1] Meaning of the "construction costs at the time of sale conversion" (= standard construction costs at the time of sale conversion) set forth in Article 9 (1) [Table 1] of the Enforcement Rule of the former Rental Housing Act as the basis for calculating the upper limit of the sale conversion price, and whether the "depreciation expenses during the rental period" to be deducted from the calculated price when calculating the said upper limit must be calculated on the basis of the housing price as of the time of the initial public notice for the recruitment of residents (affirmative) [2] Scope of "obligations arising from commercial acts" to which the statutory commercial interest rate under Article 54 of the Commercial Act applies [3] Whether the provisions of the former Rental Housing Act and other relevant statutes and regulations concerning the criteria for calculating the sale conversion price are mandatory rules (affirmative), and the effect of a sale contract concluded at a sale conversion price exceeding the amount calculated under the said calculation criteria (= void to the extent of such excess) / Whether the legal principle of such partial voidness likewise applies where a private rental housing operator carries out a sale conversion after obtaining approval for the sale conversion from the mayor, etc. (affirmative) [4] Whether a person who has violated a mandatory rule asserting the invalidity of his or her own agreement contravenes the principle of good faith (in principle, negative), and the requirements for denying the exercise of a right on the ground that it violates the principle of good faith and fair dealing [5] Meaning of the construction costs set forth in Article 9 (1) [Table 1] of the Enforcement Rule of the former Rental Housing Act as the basis for calculating the sale conversion price (= construction costs actually incurred within the scope of the standard construction costs) [6] In a case where an issue arose as to which of the tax base for acquisition tax declared for the said apartments and the result of the appraisal of the construction costs should be relied upon in recognizing the "actual construction costs" serving as the basis for calculating the sale conversion price of rental apartments that Company A had itself constructed, leased to B and others, and then sold to them upon sale conversion, a case holding that the court below's determination, which recognized the actual construction costs on the basis of the amount that Company A had declared as the tax base for acquisition tax for the said apartments, involved no error such as misapprehension of legal principles [7] Meaning of the "supply price" set forth in subparagraph 2 (ra) 2) (ga) of [Table 1] to Article 9 (1) of the Enforcement Rule of the former Rental Housing Act as the basis for calculating the land cost, which is one of the components of the sale conversion price of rental housing, and the purport of the provision of (ra) 2) (da) (1) of the said [Table 1] under which the interest for the period on prepaid land price may be added to the land cost of a public housing site / Method of calculating the land cost serving as the basis for the sale conversion price where a rental housing operator prepaying the price of a public housing site supplied to it thereby receives a partial discount on such price

Summary of the holding

The official text publishes no summary of the holding for this decision. The quotation and factors in this record are copied verbatim from the points at issue; the evidence for each axis is taken from the points at issue, the order and the reasons.

Order

원심판결을 파기하고, 사건을 서울고등법원에 환송한다.

Unofficial English translation

The judgment of the court below is reversed, and the case is remanded to the Seoul High Court.

Provisions referred to

[1] 구 임대주택법 시행규칙(2013. 3. 23. 국토해양부령 제1호로 개정되기 전의 것) 제9조 제1항 [별표 1](현행 공공주택 특별법 시행규칙 제40조 [별표 7] 참조) [2] 상법 제54조 [3] 민법 제105조, 제137조, 구 임대주택법(2012. 12. 18. 법률 제11587호로 개정되기 전의 것) 제1조(현행 민간임대주택에 관한 특별법 제1조 및 현행 공공주택 특별법 제1조 참조), 제21조 제3항(현행 삭제), 제4항(현행 삭제), 제10항(현행 공공주택 특별법 제50조의3 제1항 참조), 구 임대주택법 시행령(2013. 3. 23. 대통령령 제24443호로 개정되기 전의 것) 제23조 제8항(현행 공공주택 특별법 시행령 제56조 제7항 참조), 구 임대주택법 시행규칙(2013. 3. 23. 국토해양부령 제1호로 개정되기 전의 것) 제9조 [별표 1](현행 공공주택 특별법 시행규칙 제40조 [별표 7] 참조), 제14조(현행 공공주택 특별법 시행규칙 제40조 [별표 7] 참조) [4] 민법 제2조, 제105조 [5] 구 임대주택법 시행규칙(2013. 3. 23. 국토해양부령 제1호로 개정되기 전의 것) 제9조 제1항 [별표 1](현행 공공주택 특별법 시행규칙 제40조 [별표 7] 참조) [6] 민사소송법 제202조, 법인세법 제41조 제1항 제2호, 제112조, 법인세법 시행령 제72조 제2항 제2호, 구 지방세법(2005. 1. 5. 법률 제7332호로 개정되기 전의 것) 제111조 제5항 제3호(현행 제10조 제5항 제3호 참조), 제115조(현행 제18조 참조), 제120조(현행 제20조 참조), 제121조(현행 제21조 참조), 구 지방세법 시행령(2004. 12. 30. 대통령령 제18610호로 개정되기 전의 것) 제82조의3 제1항(현행 제18조 제1항 참조) [7] 구 임대주택법 시행규칙(2013. 3. 23. 국토해양부령 제1호로 개정되기 전의 것) 제9조 제1항 [별표 1](현행 공공주택 특별법 시행규칙 제40조 [별표 7] 참조)

Read 2026-10-25 · Cross-read 2026-10-25. All quotes matched against the official text. The Chinese-character placeholders the court used for anonymised parties are given in their Korean readings, and parenthetical Chinese-character glosses are omitted.

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