(1) A tax official shall endeavor to shorten the tax investigation period to the minimum possible, in consideration of the taxable items of investigation, the category and scale of business, complexity of investigation, etc.: Provided, That the tax investigation period may be extended in any of the following cases: <Amended on Jan. 1, 2010; Dec. 31, 2011; Jan. 1, 2014; Dec. 31, 2018>
1. Where a taxpayer obviously evades an investigation by concealing books, documents, etc. or delaying or refusing the presentation thereof;
2. Where it is necessary to investigate a place of transaction and conduct the on-the-spot confirmation of the transaction place or financial transactions;
3. Where a suspected case of tax evasion is detected or where, in the course of conducting a tax investigation, an investigation into tax offense under the Procedure for the Punishment of Tax Offenses Act is conducted;
4. Where the investigation is suspended due to a natural disaster or a labor dispute;
5. Where an official for taxpayer advocacy service or an official in charge under Article 81-16 (2) (hereinafter in this Article, referred to as "official for taxpayer advocacy service, etc.") acknowledges that additional fact-checking is required in relation to the suspicion of tax evasion;
6. Where a person subject to tax investigation applies for the extension of the tax investigation period to clarify the suspicion of tax evasion, etc. and the official for taxpayer advocacy service, etc. accepts such application.
(2) Where a tax official sets a tax investigation period pursuant to paragraph (1), the tax investigation period shall not exceed 20 days for the taxpayers whose annual income or transfer amount is less than ten billion won in the taxable period with the largest annual income or transfer amount of the entire taxable periods subject to tax investigation. <Newly Inserted on Jan. 1, 2010>
(3) Where the tax investigation period set under paragraph (2) is extended pursuant to the proviso of paragraph (1), approval is required from the head of a competent tax office for the first extension of the period; while, after the first extension, approval is required from the head of a higher tax office, and the extension period shall be extended by up to 20 days, respectively: Provided, That restriction on the tax investigation period under paragraph (2) and restriction on the extended tax investigation period under the main clause of this paragraph, shall not apply in any of the following cases: <Newly Inserted on Jan. 1, 2010; Jan. 1, 2014; Dec. 23, 2014; Dec. 31, 2019>
1. Where investigation of the details of the actual transaction is required due to suspicion of untruthful description of transaction, such as undocumented transaction and disguised or fabricated transaction;
2. Where investigation is conducted on suspicion of tax evasion using cross-border trade or suspicion of irregular expatriation of the earnings from tax evasion accrued in the Republic of Korea;
3. Where investigation is conducted on suspicion of tax evasion through the use of fake names, double-entry book-keeping, use of borrowed accounts, omission of cash transactions, etc.;
4. Where investigation is conducted on suspicion of tax evasion through property speculation using false contracts, unregistered transfer of property, etc.;
5. Where investigation is conducted on an inheritance tax or gift tax case, stake transfer, or tax offense, or simultaneous investigation is conducted for persons in an investment or trade relationship.
(4) Where it is impracticable to continue a tax investigation due to grounds prescribed by Presidential Decree, such as delay in the submission of data by a taxpayer, a tax official may suspend the tax investigation. In such cases, the suspended period shall not be counted in the tax investigation period and the extended period of tax investigation under paragraphs (1) through (3). <Newly Inserted on Jan. 1, 2010>
(5) During the period of suspending a tax investigation provided for in paragraph (4), a tax official shall not ask questions to the taxpayer to determine or correct the tax base and tax amount of national taxes; nor inspect or investigate account books, etc. or request the submission thereof. <Newly Inserted on Dec. 19, 2017>
(6) When a tax official suspends a tax investigation under paragraph (4), he or she shall immediately resume the tax investigation when the grounds for suspension are eliminated: Provided, That the tax investigation may resume when it is necessary to do so urgently, such as securing tax claims, etc. <Newly Inserted on Jan. 1, 2010; Dec. 19, 2017>
(7) When a tax official intends to extend a tax investigation period in accordance with the proviso of paragraph (1), he or she shall notify the ground and period of such extension in writing to the taxpayer; where he or she suspends or resumes a tax investigation under paragraphs 4 and 6, he or she shall notify the taxpayer of the ground thereof in writing. <Amended on Jan. 1, 2010; Dec. 19, 2017>
(8) A tax official shall endeavor to shorten the tax investigation period to the minimum possible and may close the investigation prior to the expiration of the investigation period if he or she determines that further investigation is unnecessary after reviewing the transparency of book-keeping and accounting and other taxation faithfulness of the relevant person. <Newly Inserted on Jan. 1, 2014; Dec. 19, 2017>[This Article Newly Inserted on Dec. 30, 2006][Previous Article 81-8 moved to Article 81-10 <Dec. 30, 2006>]