XBRL and iXBRL in Finland.
The complete picture.

Finland was among the earliest European countries to engage seriously with XBRL as a mechanism for structured digital financial reporting. The country's strong tradition of e-government, combined with the ambitions of the Finnish Tax Administration (Vero) and the Patent and Registration Office (PRH), created fertile ground for early adoption.

2003-2007: The SBR Finland initiative begins. Finland joined the XBRL International consortium in the early 2000s and began exploratory work on Standard Business Reporting (SBR) — a framework for standardising how businesses report financial data to government agencies. The Finnish Tax Administration led early pilots using XBRL for corporate income tax reporting, with the goal of reducing administrative burden on companies and improving data quality for tax authorities.

2008-2014: Tax reporting and the first national taxonomy. The Finnish Tax Administration deployed XBRL-based electronic filing for certain tax reporting obligations. The PRH began working alongside Vero to develop a national taxonomy that could serve both tax reporting and Trade Register financial statement filing. This collaborative approach — unusual in Europe at the time — laid the groundwork for what would become the Finnish SBR taxonomy.

2015-2019: EU-level alignment and ESEF preparation. The EU's work on the European Single Electronic Format (ESEF) began in earnest after the EU Transparency Directive amendments of 2013 mandated that listed companies file annual financial reports in a machine-readable format. ESMA (the European Securities and Markets Authority) was tasked with developing the ESEF taxonomy, and Finnish regulators — particularly FIN-FSA — began planning for its implementation in the Finnish capital markets.

2019: ESEF Regulation published. EU Commission Delegated Regulation 2019/815 established the formal requirements for ESEF, including the use of iXBRL format and the ESMA taxonomy based on IFRS. Finnish listed companies had until FY 2021 to comply. FIN-FSA began issuing guidance and worked with Nasdaq Helsinki to establish the Central Storage Facility (CSF) as the gateway for Finnish ESEF submissions.

2020-2021: ESEF goes live in Finland. Finnish listed companies filed their first ESEF iXBRL annual reports for FY 2020 on a voluntary basis, with mandatory compliance from FY 2021. The transition was broadly successful, though the sector quickly discovered the complexity of extension element anchoring and block tagging — areas that would become focus points for FIN-FSA review in subsequent years.

The European Single Electronic Format (ESEF) mandate is the most mature iXBRL requirement in Finland. It applies specifically to companies whose securities are admitted to trading on a regulated market — in practice, this means companies listed on Nasdaq Helsinki's Main Market.

What ESEF requires. Listed companies must file their Annual Financial Report (AFR) in iXBRL format. The AFR must contain IFRS consolidated financial statements tagged using the ESMA ESEF taxonomy. The filed document is a single XHTML file (the iXBRL file) packaged in a .zip archive and submitted to the Nasdaq Helsinki Central Storage Facility (CSF), which acts as Finland's Official Appointed Mechanism (OAM) for regulated information storage.

Detail tagging vs block tagging. ESEF requires two types of tagging. Detail tagging applies structured XBRL tags to individual financial figures — every line in the primary financial statements (balance sheet, income statement, cash flow, equity movements). Block tagging, mandatory from FY 2022, applies tags to entire sections of text — accounting policies, note disclosures and management commentary — as structured text blocks. Block tagging significantly increases the scope of an ESEF engagement compared to detail tagging alone.

Extension elements and anchoring. When a company's financial reporting structure contains items that don't map directly to a standard ESMA taxonomy concept — common for Finnish companies with sector-specific line items — custom "extension" elements are created. Under ESEF, every extension must be anchored to the nearest appropriate concept in the ESMA base taxonomy. Anchoring completeness is a key area of regulatory scrutiny and auditor review.

Annual taxonomy updates. ESMA updates the ESEF taxonomy annually, aligned with changes to IFRS standards. The 2025 taxonomy update included early IFRS 18 preparatory elements. Each annual filing must use the current taxonomy release — meaning extension anchoring, element mapping and validation must be reviewed every year, not just at initial implementation.

The PRH iXBRL mandate is the most significant expansion of structured digital reporting in Finland since ESEF. Where ESEF covers only a few hundred listed companies, PRH iXBRL will affect tens of thousands of Finnish businesses — from mid-market commercial companies to subsidiaries of international groups.

Why PRH is introducing iXBRL. The Finnish government's digital agenda aims to make all company financial data in the Trade Register available as structured, machine-readable information. This enables automated use of financial data by creditors, investors, credit agencies, public authorities and the Finnish Tax Administration — reducing administrative friction and improving transparency across the Finnish economy.

The three-phase rollout. The PRH iXBRL mandate is being introduced in three phases. Phase one (January 2026) makes electronic filing via ytj.fi mandatory for all Trade Register notifications and applications. Phase two (2027) introduces the iXBRL requirement for financial statements, audit reports and management reports for companies required to appoint a statutory auditor. Phase three (2028) completes the transition, making all company accounts in the Trade Register available as structured digital data.

The Finnish SBR taxonomy and ytj.fi. PRH filings use Finland's national SBR taxonomy rather than the ESMA ESEF taxonomy. Submissions are made through ytj.fi — the Finnish Business Information System portal jointly operated by the PRH and the Finnish Tax Administration. The SBR taxonomy covers both Finnish GAAP (FAS) and IFRS, allowing companies reporting under either standard to comply without changing their accounting framework.

ESEF iXBRL — Nasdaq Helsinki-listed companies. Any company whose securities (shares or bonds) are admitted to trading on the Nasdaq Helsinki Main Market must file ESEF iXBRL annually from FY 2021. This covers all issuers on the regulated market supervised by FIN-FSA. Nasdaq First North companies are not in scope for ESEF, but may be in scope for PRH iXBRL from 2027 if they meet the auditor appointment threshold.

PRH iXBRL — companies required to appoint a statutory auditor. From 2027, any Finnish company required to appoint a statutory auditor under the Finnish Auditing Act (Tilintarkastuslaki 1141/2015) must file iXBRL with the Trade Register. A company must appoint an auditor if it exceeds at least two of the following thresholds in the preceding financial year:

These thresholds are deliberately low — the vast majority of Finnish companies with any material business activity will exceed at least two of them. Sole traders and micro-companies are unlikely to be affected, but most limited companies (osakeyhtiö / Oy), co-operatives, general partnerships and limited partnerships above these thresholds will be in scope from 2027.

Exemptions. Certain company types and sizes may be exempt from the auditor appointment requirement — for example, small housing companies, certain associations and very small companies below all three thresholds. Companies should confirm their specific obligation with their auditor or the PRH.

The Finnish SBR (Standard Business Reporting) taxonomy is Finland's national XBRL taxonomy for structured digital financial reporting. It was developed collaboratively by the Finnish Tax Administration (Vero) and the PRH, with input from the Federation of Finnish Financial Services, Finnish accounting standard setters and industry representatives.

What the SBR taxonomy covers. The taxonomy provides a comprehensive dictionary of financial concepts for both Finnish GAAP (FAS, based on the Kirjanpitolaki) and IFRS. It covers balance sheet items, income statement line items, cash flow concepts, note disclosure elements and management report sections — all mapped to standardised XBRL concepts that the PRH and tax authorities can process automatically.

FAS and IFRS element sets. Companies reporting under Finnish GAAP apply the FAS element set of the SBR taxonomy. Companies reporting under IFRS — including subsidiaries of listed groups — apply the IFRS element set. Both sets are part of the same taxonomy architecture, which means a single filing can reference either without switching taxonomy frameworks.

How the SBR taxonomy differs from ESMA ESEF. The ESMA ESEF taxonomy is maintained by ESMA and aligned with international IFRS standards. The Finnish SBR taxonomy is maintained by Finnish authorities and reflects Finnish accounting law, including the specific disclosure requirements of the Kirjanpitolaki and the accounting standards issued by the Finnish Accounting Standards Board (KILA). Companies that file both ESEF and PRH iXBRL must use both taxonomies — the ESMA taxonomy for the ESEF consolidated filing and the Finnish SBR taxonomy for PRH subsidiary filings.

Taxonomy updates. The SBR taxonomy is updated periodically to reflect changes in Finnish accounting standards, KILA guidance and EU reporting requirements. XBRTags tracks all SBR taxonomy updates as they are released and ensures that every PRH iXBRL engagement uses the current taxonomy version.

The December 2023 amendment. The Finnish Securities Markets Act (Arvopaperimarkkinalaki) was amended on 21 December 2023 (law 1260/2023) to introduce a mandatory assurance obligation for ESEF filings. This requirement came into force immediately, applying to annual reports filed for periods ending after the amendment date.

What the assurance obligation requires. An issuer's auditor (KHT or HT, i.e., the statutory auditor of the listed company) must either audit the ESEF financial statements or perform an equivalent ISAE 3000 assurance engagement. The scope covers three layers: the human-readable financial statements and their consistency with the audited accounts; the machine-readable XBRL data layer and its consistency with the human-readable layer; and the accuracy of taxonomy mapping, including the completeness and appropriateness of extension element anchoring.

What this means for listed companies. Listed companies must ensure that their iXBRL file is of audit-grade quality — meaning the tagging decisions must be fully documented, the anchoring must be defensible and traceable, and the file must be consistent across both the human-readable and machine-readable layers. A file that passes ESMA validation rules but has incorrect tag selections or incomplete anchoring documentation will create problems during the auditor's ISAE 3000 review.

What this means for KHT and HT auditors. Audit firms delivering the ISAE 3000 engagement need documentation to support their assurance procedures. This includes a mapping walkthrough (explaining every tagging decision), an anchoring review report (documenting extension element anchoring), tag-level reconciliation (matching XBRL values to the human-readable statements) and working papers formatted for inclusion in the audit file.

IFRS 18 — a major change to the ESEF taxonomy. IFRS 18 (Presentation and Disclosure in Financial Statements), issued by the IASB and effective for periods beginning on or after 1 January 2027, replaces IAS 1. It introduces new requirements for categorising income and expense items and requires greater specificity in the income statement structure. ESMA is updating the ESEF taxonomy to reflect IFRS 18, and the FY 2027 taxonomy will include new elements for management-defined performance measures and the new income statement categories. Finnish listed companies that adopt IFRS 18 early (some from FY 2025) will need to apply the IFRS 18-aligned taxonomy elements from their first IFRS 18 period.

PRH iXBRL implementation — 2026 and 2027. The most significant near-term change for the majority of Finnish companies is the PRH iXBRL mandate. Finnish businesses should begin preparation now — running dry-run filings to identify taxonomy mapping gaps, reviewing management report structures for SBR compatibility, and confirming whether they are in scope under the auditor appointment thresholds. The PRH has indicated it will provide test environments for companies to validate iXBRL files before the mandate comes into force.

Potential extension of assurance requirements to PRH iXBRL. As of mid-2026, the assurance obligation for ESEF applies only to listed companies. However, industry discussion in Finland has raised the question of whether a similar requirement could eventually be introduced for PRH iXBRL filings — particularly for larger commercial companies or subsidiaries of listed groups. No formal proposal is currently in progress, but Finnish audit firms are beginning to prepare for this possibility.

EU Omnibus Regulation and CSRD overlap. The EU Corporate Sustainability Reporting Directive (CSRD) introduces sustainability reporting requirements with structured tagging requirements of their own (using ESRS taxonomy, delivered via iXBRL). For Finnish listed companies already filing ESEF iXBRL, CSRD will introduce an additional dimension of structured reporting — potentially in the same Annual Financial Report file. The interaction between ESEF and CSRD tagging is being resolved at ESMA level, but Finnish companies should be aware that structured reporting obligations are likely to expand significantly over the 2025-2028 period.