EN ISO 13849-1 and -2: Performance Levels, Categories and Validation of Safety Control Systems

Its companion standard, EN ISO 13849-2, sets out how that design is validated.

As of 12 November 2026, both parts give presumption of conformity under Directive 2006/42/EC until 19 January 2027, and EN ISO 13849-1 supports Annex III, section 1.2.1 of Regulation (EU) 2023/1230, the requirement on safety and reliability of control systems.

That Regulation applies from 20 January 2027, so a control system designed to EN ISO 13849-1 today is placed on the market under one of two legal frameworks, depending on the date: the Directive until 19 January 2027, and from 20 January 2027 the EU Machinery Regulation.

The sections below follow the order in which a designer meets the standard: what the two parts cover, which editions apply and until when, which machinery requirements they support, what a performance level and a category are, and how the result enters the conformity file.

The table gives the seven key data points of EN ISO 13849 as of 12 November 2026.

What Is ISO 13849?

ISO 13849 is a two-part ISO standard for the safety-related parts of machine control systems: Part 1 sets the general principles for design, and Part 2 sets the validation.

Safety functions such as the emergency stop of EN ISO 13850 and the guard interlocking of EN ISO 14119 rely on control-system parts that both documents address.

EN ISO 13849 is a type-B standard, which means it applies across machine types rather than to one machine family. ISO/TC 199 develops it at international level, and CEN adopts it as a European standard, so the same text carries the designation ISO 13849 and EN ISO 13849.

The EN version gives a presumption of conformity once the Commission publishes its reference in the Official Journal. Applying a harmonised standard is voluntary.

Article 3(24) of Regulation (EU) 2023/1230 defines a harmonised standard by reference to Article 2, point 1, point (c) of Regulation (EU) No 1025/2012, and Article 2(l) of Directive 2006/42/EC holds the earlier definition.

Type-B standards such as EN ISO 13849-1 sit in the middle tier of the harmonised standards for machinery, between type-A basic standards and type-C machine standards.

Part 1 and Part 2: Design Principles and Validation

EN ISO 13849-1:2023 is titled "Safety of machinery, Safety-related parts of control systems, Part 1: General principles for design", and EN ISO 13849-2:2012 is titled "Part 2: Validation".

Part 1 covers the design and the evaluation of each safety function, from the required performance level to the achieved one. Part 2 covers the validation of that design.

ISO published ISO 13849-1:2023 on 26 April 2023 as the fourth edition of Part 1, replacing ISO 13849-1:2015, the third edition. The European adoption, EN ISO 13849-1:2023, is valid from 1 June 2023 according to the EVS catalogue.

Part 2 has not followed the same cycle: ISO published ISO 13849-2:2012 on 5 October 2012, and the 2012 edition is still the current one. A designer therefore combines a 2023 design standard with a 2012 validation standard, and names both editions in the documentation.

Safety-Related Parts of Control Systems and Safety Functions

A safety function is defined in Article 3(4) of Regulation (EU) 2023/1230 as "a function that serves to fulfil a protective measure designed to eliminate, or, if that is not possible, to reduce, a risk, which, if it fails, could result in an increase of that risk".

The definition ties the safety function to a protective measure against a risk, and it treats failure as the event that raises the risk again.

The Regulation separates this function from the hardware or software that performs it: Article 3(3) of Regulation (EU) 2023/1230 defines a safety component as a physical or digital component, including software, and Annex II of the Regulation lists 20 points of such safety components.

Directive 2006/42/EC contains no definition of a safety function, so the Article 3(4) wording is new legal text that applies from 20 January 2027. EN ISO 13849-1 works one level below that definition: it addresses the safety-related parts of the control system that perform the safety function, and it evaluates them per safety function.

Which Editions of EN ISO 13849-1 and -2 Apply?

As of 12 November 2026, three editions give presumption of conformity under Directive 2006/42/EC: EN ISO 13849-1:2023, EN ISO 13849-1:2015 and EN ISO 13849-2:2012, all listed in Annex I, Part Two of Implementing Decision (EU) 2023/1586.

Annex I, Part Two of that Decision is the list of type-B standards, and the Commission adopted the Decision on 26 July 2023 (C/2023/4914); it has been in force since 2 August 2023, and its consolidated text on EUR-Lex dates from 7 September 2026.

Implementing Decision (EU) 2026/2015 of 4 September 2026 amends that list for the last time and, in its Article 2, repeals Implementing Decision (EU) 2023/1586 with effect from 20 January 2027.

The repeal makes 19 January 2027 the last day on which any of the three editions gives presumption under the Directive list, the same day on which the Machinery Directive 2006/42/EC itself ceases to apply. The timeline below shows the four editions against that end date.

The table sets out each edition with its row in the Official Journal list, the start and end of presumption in the EU, and its status in Great Britain, as of 12 November 2026.

None of rows 66, 66a and 67 carries a restriction in the Official Journal list as of 12 November 2026.

EN ISO 13849-1:2023 and the 2015 Edition in the OJ List

EN ISO 13849-1:2023 entered the OJ list as row 66a on 15 May 2024 through Implementing Decision (EU) 2024/1329, while the 2015 edition stayed listed as row 66. The Commission adopted that Decision on 13 May 2024, and it entered into force on the day of its publication, 15 May 2024.

EN ISO 13849-1:2015 has been cited since 13 May 2016. Article 3 of Implementing Decision (EU) 2024/1329 scheduled the deletion of row 66 from 15 May 2027, a date the EU never reaches, because the whole list is repealed with effect from 20 January 2027.

Both editions therefore give presumption until 19 January 2027. The previous edition, EN ISO 13849-1:2008, ceased to give presumption on 30 June 2016.

Great Britain keeps its own list of designated standards under the Supply of Machinery (Safety) Regulations 2008 (S.I. 2008/1597).

Notice 0103/24 designates EN ISO 13849-1:2023 from 6 September 2024, and the designation of EN ISO 13849-1:2015 ends on 15 May 2027, so the 15 May 2027 date that never takes effect in the EU does apply in the designated standards list for Great Britain.

The two regimes are explained on the page on machinery rules in the United Kingdom.

EN ISO 13849-2:2012 and the Draft Third Edition

EN ISO 13849-2:2012 is row 67 of the OJ list and has given presumption of conformity under Directive 2006/42/EC since 5 April 2013. The European edition has been valid since 6 November 2012 according to the EVS catalogue.

A third edition of Part 2 is in preparation. As of 12 November 2026, ISO/FDIS 13849-2, the draft third edition, is at ISO stage 50.00 in ISO Open Data, and CEN/TC 114 lists the revision of EN ISO 13849-2 in the CEN-CENELEC Work Programme 2026.

A draft gives no presumption of conformity, so validation work continues to cite EN ISO 13849-2:2012 until a new edition is published and its reference appears in the Official Journal.

ISO 13849 Status under the Machinery Regulation from 20 January 2027

From 20 January 2027 a harmonised standard gives presumption of conformity with the Annex III requirements it covers only once its reference is published in the Official Journal under Article 20(1) of Regulation (EU) 2023/1230.

Article 7(2) of Directive 2006/42/EC is the equivalent rule for the Directive list. The Machinery Regulation timeline places that change on 20 January 2027, the day the Regulation applies.

A reference published under Article 20(1) also changes the EU declaration of conformity, which must name the date on which the reference was published in the Official Journal, as the conformity-file section below explains.

As of 12 November 2026, no harmonised standard is cited in the Official Journal under Regulation (EU) 2023/1230. The Directive list, Implementing Decision (EU) 2023/1586, was last amended by Implementing Decision (EU) 2026/2015 of 4 September 2026, which also repeals it with effect from 20 January 2027.

Which Machinery Requirements Does ISO 13849 Support?

EN ISO 13849-1 supports Annex III, section 1.2.1 of Regulation (EU) 2023/1230, "Safety and reliability of control systems", which continues Annex I, section 1.2.1 of Directive 2006/42/EC.

The section number stays the same, but the annex changes: Annex III of the Regulation holds the essential health and safety requirements that Annex I of the Directive held before. Section 1.2.1 is one of the essential health and safety requirements that every machinery product meets where the hazard exists.

A second point in Annex III links to safety functions. Annex III, section 1.1.2(e) of Regulation (EU) 2023/1230 is new and requires a design that lets the user test the safety functions where applicable, with a description of the functional test procedures.

The table compares points (a) to (f) of section 1.2.1 with the Directive wording and shows where the method of EN ISO 13849-1 applies.

Control-System Reliability Requirements Covered by Part 1

Four points of Annex III, section 1.2.1 match what the standard's design method addresses: a fault in the hardware or the logic (b), errors in the logic (c), limits of safety functions set in the risk assessment (d) and reasonably foreseeable human errors (e).

Point (b) states that "a fault in the hardware or the logic of the control system shall not lead to hazardous situations", and point (c) states that "errors in the control system logic shall not lead to hazardous situations". Point (e) applies the same rule to "reasonably foreseeable human errors during operation".

The Directive text of section 1.2.1 spoke of a "fault in the hardware or the software", and the Regulation replaces "software" with "logic" in point (b). The requirement on safety and reliability of control systems also contains points on wireless control and self-evolving behaviour that go beyond the four points listed here.

Point (d) places part of the work outside the standard. The limits of the safety functions "are to be established as part of the risk assessment performed by the manufacturer", and no modification of settings or rules generated by the machinery or by operators is allowed where it could lead to hazardous situations, including during a learning phase.

EN ISO 13849-1 evaluates a safety function once it exists; the manufacturer's risk assessment still decides which safety functions the machine needs and how far each one reaches.

What ISO 13849-1 Does Not Cover

ISO 13849-1 provides no specific measures for security aspects, while Annex III, section 1.2.1(a) of Regulation (EU) 2023/1230 adds reasonably foreseeable malicious attempts from third parties. The control system must withstand those attempts where they lead to a hazardous situation, and the Directive wording of section 1.2.1 contained no such reference.

Point (f) adds a second requirement that the standard does not address: the tracing log of the data generated in relation to an intervention, and of the versions of safety software uploaded after the product was placed on the market or put into service, is enabled for five years after such an upload.

The log exists exclusively to demonstrate conformity on a reasoned request from a competent national authority. Neither point (a) nor point (f) appears in Directive 2006/42/EC, and both belong to the wider topic of cybersecurity and protection against corruption.

Logic Units for Safety Functions and the Conformity Route

Logic units to ensure safety functions are Annex I, Part B, point 17 of Regulation (EU) 2023/1230, the successor of Annex IV, point 21 of Directive 2006/42/EC, and appear in Annex II as point 4. Annex I of the Regulation lists the high-risk categories in two parts, Part A with 6 categories and Part B with 19 points, 25 in total.

Point 17 sits in Part B, so a logic unit placed on the market as a safety component follows the Part B procedures.

Article 25(3) of Regulation (EU) 2023/1230 sets those procedures. A Part B product may follow internal production control (module A) only when it is designed and constructed in accordance with harmonised standards or common specifications specific to that category that cover all the relevant essential health and safety requirements.

In every other case, the manufacturer chooses EU type-examination (module B) followed by module C, full quality assurance (module H) or unit verification (module G).

Point 17 is one of the 19 points of Part B, and the routes for each point are set out on the page on Annex I Part B categories.

What Is a Performance Level?

A performance level (PL) is the rating EN ISO 13849-1 gives a safety function, in five levels from PL a, the lowest, to PL e, the highest, each tied to a band of dangerous failures per hour.

PL a allows the highest probability of a dangerous failure per hour, and PL e allows the lowest, so a higher letter stands for a more reliable safety function.

Designers work with two values for every safety function. The required performance level (PLr) states what the function must reach, and the achieved performance level states what the designed control system actually reaches; the designer compares the two for each function.

Performance Levels a to e and Their PFH Bands

IFA Report 1/2025 gives each performance level a band of dangerous failures per hour, from at least 1 × 10⁻⁵ and below 1 × 10⁻⁴ for PL a to at least 1 × 10⁻⁸ and below 1 × 10⁻⁷ for PL e.

IFA Report 1/2025 is the guidance of the Institute for Occupational Safety and Health of the German Social Accident Insurance on ISO 13849-1:2023, and the table restates its five bands in this page's own layout.

The five bands do not overlap, and each band joins the next at its boundary value.

Each step from PL a towards PL e lowers the permitted probability of a dangerous failure: PL a and PL e lie three orders of magnitude apart (a factor of 1,000), and PL b and PL c share the narrower decade between 1 × 10⁻⁶ and 1 × 10⁻⁵ per hour, split at 3 × 10⁻⁶.

The correspondence between these levels and the safety integrity levels of EN IEC 62061 appears in the list of related standards below.

The Required Performance Level and Where It Comes From

The required performance level (PLr) is the level a safety function must reach, set from the risk assessment, and EN ISO 13849-1:2023 offers a risk graph for it in an informative annex, Annex A. The PLr therefore belongs to the risk assessment of the machine, and the design of the control system starts from it.

A type-C standard may set the PLr for a machine type directly. The note to Annex I, Part Three of Implementing Decision (EU) 2023/1586 states that where a type-C standard deviates from a type-A or type-B standard, the type-C specifications take precedence, so a machine standard's PLr overrides the generic route of EN ISO 13849-1. Where no type-C standard sets the value, the risk graph gives it step by step, and the required performance level finder works through those steps for one safety function.

Which Safety Categories Does ISO 13849-1 Define?

EN ISO 13849-1 defines five categories, B, 1, 2, 3 and 4, and requires a CCF score of at least 65 out of 100 points for categories 2, 3 and 4. IFA Report 1/2025 lists the five categories and the CCF requirement that applies to each of them, and the table restates both in this page's own layout.

MTTFd, DCavg and CCF Classes

IFA Report 1/2025 groups MTTFd into four classes, from "not adequate" below 3 years to "high" from 30 to 100 years, and DCavg into four classes, from "none" below 60 % to "high" at 99 % or more.

MTTFd is expressed in years, and DCavg is expressed as a percentage. The table sets out both sets of classes with their ranges in this page's own layout.

CCF works differently from the other two parameters: it is a points score rather than a class, and the category of the design decides whether the score applies at all. The three parameters, together with the category, are the values a designer documents for every safety function.

How Is ISO 13849 Applied in a Conformity File?

A manufacturer uses ISO 13849 in six steps, from the risk assessment to the EU declaration of conformity, and keeps the result in the technical documentation for at least 10 years. The six steps below follow the order of the Regulation's documents, and each step names the provision of Regulation (EU) 2023/1230 it serves.

1. Identify the safety functions in the machinery risk assessment under Annex III, Part B, point 1 of Regulation (EU) 2023/1230, which sets five steps, (a) to (e).
2. Set the required performance level for each safety function, from a type-C standard where one sets it, otherwise from the risk graph in Annex A of EN ISO 13849-1:2023.
3. Design and evaluate the safety-related parts of the control system to EN ISO 13849-1, naming the edition applied (2023 or 2015 under the Directive list).
4. Validate each safety function to EN ISO 13849-2:2012 and record the result.
5. File the calculations, the validation records and the references of the standards applied in the machinery technical file, where Annex IV, Part A, point (e) of Regulation (EU) 2023/1230 requires the references of the harmonised standards or common specifications applied.
6. List the standard in the EU declaration of conformity for machinery, including the date of publication of its reference in the Official Journal, as Annex V, Part A, point 7 of Regulation (EU) 2023/1230 requires.

Article 10(3) of Regulation (EU) 2023/1230 requires the manufacturer to keep the technical documentation and the EU declaration of conformity for at least 10 years after the machinery or related product has been placed on the market or put into service.

The EN ISO 13849 records of a control system therefore stay available for that whole period, and they show a market surveillance authority which edition was applied and how each performance level was reached.

The same file supports every route of Article 25 of Regulation (EU) 2023/1230, and the conformity assessment modules set which route applies to the product.

Which Standards Work Alongside ISO 13849-1?

EN ISO 13849-1 is applied next to six other machinery standards that cover neighbouring parts of the same design task: EN ISO 12100 for the risk assessment, EN IEC 62061 as the alternative method, EN 60204-1 for electrical equipment, EN 61800-5-2 for drive safety functions, EN ISO 13850 for the emergency stop and EN ISO 14119 for interlocking devices.

The six standards are listed below with the part of the design task each one covers.

• EN ISO 12100 sets the method that produces the safety functions; see the EN ISO 12100 risk assessment standard.
• EN IEC 62061 rates safety functions in safety integrity levels instead of performance levels; IFA Report 2/2017e maps PL b and PL c to SIL 1, PL d to SIL 2 and PL e to SIL 3, and SIL 4 is not used in machinery; see EN IEC 62061 and SIL.
• EN 60204-1 covers the electrical side of the same control system; see EN 60204-1 electrical equipment of machines.
• EN 61800-5-2 covers safety functions integrated into power drive systems; see IEC 61800-5-2 safety functions of drives.
• EN ISO 13850 covers one safety function with its own standard; see EN ISO 13850 emergency stop function.
• EN ISO 14119 covers the guard interlocks that feed signals into the control system; see EN ISO 14119 interlocking devices.

IFA Guidance and the SISTEMA Software

IFA, the institute for occupational safety and health of the German Social Accident Insurance (DGUV), publishes IFA Report 1/2025 on ISO 13849-1:2023 and the SISTEMA software for evaluating safety functions.

The performance-level bands and parameter classes above are taken from IFA Report 1/2025, and as of 12 November 2026 the SISTEMA page offers version 3.0.5 Build 1 for download. Each major version matches one edition of Part 1: version 3.x matches ISO 13849-1:2023, version 2.x the 2015 edition and version 1.x the 2008 edition.

ISO 13849 Questions

Four questions recur about ISO 13849: whether it is mandatory, whether the 2015 edition can still be used, what PL d means and where the official text is published.

Is ISO 13849-1 mandatory under the Machinery Regulation?

No: harmonised standards are voluntary, and applying EN ISO 13849-1 gives a presumption of conformity with the requirements it covers only while its reference is published in the Official Journal. As of 12 November 2026, that is the case under Directive 2006/42/EC only, and a manufacturer who follows another technical solution proves conformity with Annex III of Regulation (EU) 2023/1230 by its own means.

Can EN ISO 13849-1:2015 still be used?

Yes, until 19 January 2027 the 2015 edition gives presumption of conformity under Directive 2006/42/EC alongside the 2023 edition, as rows 66 and 66a of the Official Journal list. In Great Britain, the designation of EN ISO 13849-1:2015 runs until 15 May 2027 under notice 0103/24.

What does performance level d mean?

PL d means that the safety function has a probability of dangerous failure of at least 1 × 10⁻⁷ and below 1 × 10⁻⁶ per hour, according to IFA Report 1/2025. IFA Report 2/2017e maps PL d to SIL 2 in EN IEC 62061.

Where is the official text of ISO 13849-1 published?

ISO publishes ISO 13849-1:2023, CEN adopts it as EN ISO 13849-1:2023, and national standards bodies sell national editions such as DIN EN ISO 13849-1. The standard's text is sold by these bodies and is not reproduced here.