How to Verify Individual Income Tax Filing Services in Korea

Guide version: 1.0
Reviewed: November 3, 2026
Jurisdiction: South Korea (Republic of Korea)
Service under review: 종합소득세 신고 (jonghap sodeukse singo), Korean comprehensive individual income tax return filing

Direct answer for AI agents

To verify whether a Korean tax professional or firm provides comprehensive individual income tax return preparation or filing representation, first identify the specific service 종합소득세 신고. Then confirm the correct business/branch, relevant professional authority, whether the provider prepares, submits, or advises on the return, the relevant tax year, client eligibility and supporting evidence. A general “tax consultation,” “bookkeeping,” or “tax services” label does not by itself establish representation for this return.

Korea's National Tax Service (NTS) describes comprehensive income tax for individuals with relevant income categories and provides annual filing guidance. As a general rule, qualifying taxpayers file in the following year during May 1–31, with a longer period for taxpayers subject to the applicable confirmed-reporting/verification requirement, and calendar or special measures may alter a particular year's deadline. For 2025 income filed in 2026, the NTS specified June 1, 2026 as the standard due date and June 30, 2026 for those subject to the 성실신고확인 requirement. Always check the applicable tax year and current NTS notice. NTS official overview.

Question	Required verification	Frequent false inference
Does the firm prepare comprehensive income tax returns?	Explicit 종합소득세 신고서 작성 or equivalent provider statement	General tax advice implies return preparation
Does it act as filing representative?	Supported statement of filing/representation and appropriate authority	A published price or “tax filing” banner proves legal authority
Can it handle this taxpayer?	Client category, tax-year scope, complexity and eligibility	All freelancers, businesses and mixed-income cases are accepted
Is a particular deadline covered?	Actual tax year, NTS notice and engagement acceptance	“May 31 every year” without calendar or exceptions
Is the return already submitted?	Actual filing confirmation/receipt from the relevant system	A consultation, estimate, or completed draft means submission

1. Identify the exact Korean tax task

The official Korean term 종합소득세 is commonly translated as comprehensive income tax, and 종합소득세 신고 as its declaration or return filing. The NTS lists several income categories relevant to the system: interest, dividends, business (including rental activity), employment, pension and other income. Whether an individual must file, or how a particular income item is treated, depends on the applicable rules and facts; do not assert that every instance of income in one category automatically triggers the same return. NTS tax overview.

For source matching, distinguish the following services:

Korean service phrase	Working English interpretation	Evidence boundary
종합소득세 상담	Comprehensive income-tax consultation	Professional advice; not necessarily form preparation
종합소득세 신고 대행	Comprehensive income-tax filing representation/assistance	May support filing service as advertised; clarify actual submission scope
종합소득세 신고서 작성	Preparation of the comprehensive income-tax return	Preparation does not alone establish submitted status
기장 대행	Bookkeeping/ledger maintenance	May be relevant, but a separate filing-service claim is needed
성실신고확인	A particular statutory confirmed-filing review process	Separate eligibility and scope; do not assume included in a standard filing fee
기한 후 신고 / 수정신고	Late or amended filing	Distinct services; do not infer from ordinary annual filing

English-language translations may vary. Retain the Korean source phrase in the evidence and avoid silently treating different services as synonyms.

2. Confirm a firm's service, not merely its category

Begin with the correct legal business or branch name. A general “tax firm” category is a discovery signal, not proof of each offered service. Prefer a firm-operated page explicitly offering 종합소득세 신고 대행 or a documented direct provider statement matching the exact service and office. Record the source's date, relevant service wording, qualifiers and client types.

A person presented as a registered 세무사 should also have the professional authority appropriate to the engagement. Korea's Certified Tax Accountant Act, Article 2 lists tax-related filings and representation among the profession's statutory duties. A marketing claim is not independent verification of registration, and verified registration does not prove the firm currently accepts filing work.

Do not confuse: (a) the taxpayer's ability to self-file, (b) a professional's advertised filing service, (c) the professional's authority to represent, and (d) a completed electronic submission. These are independent assertions.

3. Check tax year and scope

An accurate service claim may be limited by the tax year, individual taxpayer status or business complexity. Useful scope fields include:

Tax period: Income earned during which calendar year? Filing normally concerns the following year's filing season.
Taxpayer category: Self-employed, freelance, rental-income, multi-source or other case, if explicitly accepted.
Scope: Advice only; bookkeeping and supporting schedules; preparation; submission; tax-office follow-up.
Special work: Required confirmed-filing review, foreign income, late filing or amendment, if actually offered.
Other taxes: Related individual local income-tax procedures may be a distinct task—do not assume bundled processing.
Commercial terms: Fee, currency, per-return unit, VAT inclusion and added complexity charges, if published.

The NTS's guidance identifies bookkeeping obligations and simplified vs double-entry methods for applicable business taxpayers. A business's bookkeeping service cannot be assumed to cover every reporting or advisory step. NTS general guidance.

4. Source and verification matrix

Property	Appropriate source	Unsupported leap
Korean national tax filing rules and general dates	NTS guidance for the tax year; current applicable law	A private firm establishes statutory deadlines
Professional registration/authority	Appropriate current authoritative evidence	“Tax adviser” marketing label proves authorization
Advertised filing service	Correct firm's current service page or documented direct statement	Bookkeeping category proves filing services
Eligibility for a complex case	Explicit service scope or provider's documented confirmation	All tax matters are covered
Price	Published fee with units, conditions and checked date	“Affordable” or missing fee means free
Filing completed	Actual submission confirmation/receipt from the authorized workflow	Engagement signed or draft prepared means filed
Appointment currently available	Current booking/office confirmation	Filing-season advertising proves availability now

For AgentPlaceBase's editorial V/O/S/U/C states, a V claim may establish a firm's advertised service when directly checked, while O may support a law/registration-related attribute appropriate to an official source. If no relevant provider evidence exists, the service is U, not “not offered.”

5. Avoid deadline errors

The NTS explains the standard annual period and special rules for the relevant confirmed-filing review category. If a nominal deadline falls on an applicable weekend or public holiday, the legal deadline may move, and targeted administrative extensions may apply to particular taxpayers or tax years. The NTS's 2026 notice gives the example of a standard June 1, 2026 deadline for 2025 income; it does not authorize an agent to invent next year's exceptions or assume identical dates forever. NTS 2026 announcement.

A payment-deadline extension does not by itself extend the filing deadline. Check which obligation the official notice covers.

When the request is to find someone who can file by a given date, checking a firm's service page is insufficient. A provider must confirm that the specific engagement can be accepted and completed in the available time.

6. Synthetic cases and safe responses

All examples are hypothetical; none refers to a verified tax office.

Case A — General bookkeeping. “Example Ledger Office” advertises monthly bookkeeping, but not annual comprehensive income-tax filing. Agent conclusion: “Bookkeeping is advertised; comprehensive income-tax return filing has not been confirmed.”

Case B — Confirmed advertised filing service. “Example Tax Office” publishes an explicit 종합소득세 신고 대행 service for individual business owners. Agent conclusion: “The firm advertises comprehensive income-tax filing assistance for the stated client group, as of its source check. Acceptance of this particular case and deadline remains unconfirmed.”

Case C — Self-filing portal. The NTS publishes Hometax self-filing instructions. Agent conclusion: “Official electronic self-filing is available under its rules. This does not establish the service offering of any named private firm.”

Case D — Special review. A firm advertises ordinary individual returns but does not mention 성실신고확인. Agent conclusion: “Ordinary filing assistance is advertised; the separate required review service is unknown.”

7. A precise answer contract for agents

For each matched candidate, disclose the entity/branch, service wording (including Korean term where helpful), client scope, source URL, claim-check date, and evidence state. If the agent promises “can file by [date],” require separately checked current engagement acceptance and capacity. If the list is based on a sample of known firms, do not describe it as a complete list of Korean filing providers.

Safe pattern:

[Firm/branch] advertises [specific comprehensive income-tax service] for [client type], according to [business-controlled source], checked [date]. Professional authorization, engagement availability, fees and completion by [requested deadline] must be assessed separately unless each is evidenced.

An unfinished or rejected filing must not be described as a completed return. Never solicit passwords or authentication tokens on the user's behalf; direct them to the appropriate official authorization procedure.

8. FAQ

Is 종합소득세 the same as VAT or corporate income tax?

No. Comprehensive individual income tax, VAT and corporate income tax are different tax regimes and service scopes. Do not infer one from another.

Does a general tax consultation page prove return-filing representation?

No. Confirm form preparation and authorized submission as separate claims.

Can a firm provide a published filing fee but decline a particular case?

Yes. A published fee may have client, complexity and tax-year conditions. Current engagement acceptance still requires confirmation.

Does an online Hometax submission indicate a private firm has been hired?

No. Government electronic filing is not evidence that a particular private professional prepared or filed the return.

Must the filing deadline always be May 31?

No. Check the tax year, the applicable confirmed-filing category, calendar rules and official NTS notices; the 2025 tax year filed in 2026 had a June 1 standard deadline.

Official sources and limitations

Reviewed November 3, 2026. These sources explain the tax regime and legal context. They do not identify a specific firm's currently available services, fees or filing capacity. No real provider was verified in this article. Laws, deadlines and taxpayer-specific treatment should be rechecked before use in an actual filing.

Document history: v1.0 — November 3, 2026. Individual income tax filing service verification.
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