SAP Custom Code and Clean Core Statistics (2026): Unused Code, Remediation and Readiness

Most SAP custom code is still running in production, and each object still needs a decision: retire it, remediate it, or redesign it as a clean core extension. This roundup collects the published numbers behind those decisions. Each figure lists its year, its population where the source states one, and a link to the source.

Key takeaways

Adoption and migration status

The adoption picture depends heavily on how a survey defines "migrated." The two 2026 benchmarks below use different definitions, so they should not be stacked on top of each other.

• SAPinsider surveyed 296 organizations between December 2025 and March 2026 for its ERP Migration and Transformation benchmark (Datapace summary of SAPinsider data, 2026).
• Although 55% of companies report having deployed SAP S/4HANA, only 34% indicate a complete transition (SAPinsider, 2026).
• Another 36% of respondents are still implementing, evaluating or building a business case, 4% report a project on hold, and 5% have no plans (SAPinsider, 2026).
• Among deployers, cloud and traditional deployments are close: 26% run SAP S/4HANA Cloud and 29% run the traditional product (SAPinsider, 2026).
• In a separate ASUG and Precisely study, 59% of companies are now fully or partially live on SAP S/4HANA, up 13 percentage points from 2024 (Precisely and ASUG, November 2025).
• The same study found that nearly two-thirds of companies (64%) will be fully live or in the process of migrating to S/4HANA by the end of 2025 (Precisely and ASUG, November 2025).

Source: Precisely and ASUG, Nov 2025; SAPinsider, 2026

The deadline itself is well documented. Mainstream maintenance for SAP Business Suite 7 ends in December 2027. (Pinnacle Consulting, 2026). Three further figures frame the pace:

• In the SAPinsider survey, 43% of organizations named SAP's AI announcements as the primary external factor shaping their ERP strategy, ahead of the maintenance deadline at 39% (SAPinsider, 2026).
• A Gartner estimate reported by CIO puts the base at 35,000 SAP ECC customers. The same estimate says only about 39% of SAP's roughly 35,000 ECC customers had started the move to S/4HANA by the end of 2024 (Assima, citing Gartner via CIO). Note that Datapace, citing the same figure, describes the 39% as having migrated to S/4HANA by the end of 2024 (Datapace, 2026). The two sources disagree on whether that means started or finished, so treat it as an unresolved definition.
• Among organizations with an approach chosen, ASUG research shows the split is nearly even: 34% pursuing brownfield, 33% greenfield and 20% hybrid (Pinnacle, citing ASUG research, undated).

Source: Pinnacle Consulting citing ASUG research, undated

Custom code volume and reliance

• 95% of organizations surveyed build and run custom ABAP code to extend SAP software applications (ASUG Research and smartShift, study of 174 members, year not stated).
• In a 2026 ASUG study of 168 members, ninety-two percent of respondents expect to carry custom code into SAP S/4HANA, and 64% expect to retain more than one-quarter of their existing custom code landscape (ASUG Research Report, 2026).
• A figure attributed to a joint ASUG and Pillir study says ninety one percent of SAP users report relying heavily on custom code to run mission-critical business processes (2Data, citing ASUG and Pillir, year not stated). We could not retrieve the original report, so treat this as secondhand.
• The same secondhand summary gives an average annual maintenance cost of eight hundred thousand dollars for the most valuable custom code (2Data, citing ASUG and Pillir).
• One ASUG-linked summary reports that 44% of SAP customers cite having too many customisations in their old instances as their number one S/4HANA migration challenge (smartShift, citing ASUG research, year not stated).

Source: ASUG Research Report (hosted by smartShift), 2026, 168 qualified members

Unused and retirable custom code

This is the most-quoted number in the category, and it is also the least consistent. Sources differ on whether they measure never-executed objects, objects unused for 12 months, or objects a scoping exercise would retire. Read the chart as a list of low-end figures, not as one benchmark.

• A SAP PRESS author writes that you have a big list of the 60% to 75% of your custom code objects that are never called (SAP PRESS, undated, roughly three years old). This is historical and not an SAP-published study.
• SAP's own Custom Code Migration tooling works from usage data to define which custom code moves forward, and it can generate a deletion transport for unused code during conversion (SAP Help, Custom Code Migration guide, 2023 edition).
• An SAP-hosted 2022 webinar deck states that only 20% of existing modifications are used, attributed to "statistics" without naming a source (SAP clean core webinar deck, 2022). This measures modifications, not all custom objects, so it is not comparable to the other figures.
• A TotalTek article says 20–40% of custom objects are unused for over 12 months (TotalTek, undated). The article does not name the underlying study.
• A smartShift guide cites industry benchmarks that place 40% to 60% of custom code in an average SAP repository as technically unused (smartShift, undated). The benchmark is unnamed.
• In highly individualized landscapes, between 60 and 80 percent of this is no longer used (e3mag, 2025 or 2026).
• smartShift's own migration experience suggests 25–40% of objects can be retired (smartShift, undated). This is vendor data.
• Axxis Consulting reports from its own engagements that 40% to 50% of custom code in regional SAP systems is no longer even in use (Axxis Consulting, 2026). This is vendor data.
• An ERP Decision Office guide estimates 30-50% may be retired (ERP Decision Office, undated). The estimate is not attributed to a study.

Source: Mixed vendor and practitioner sources, 2024 to 2026. Each bar is the low end of the source's own range. See the links in the list above for each source's date and method.

A few claims circulate without a traceable origin. One widely shared article says some sources claim up to 60% of custom code is identified as unused during ECC to S/4HANA migrations, and its author cautions that retirement is harder in practice than the number suggests (Boring Enterprise Nerds, March 2026).

Clean core readiness and awareness

• Three out of four SAP customers are now aware of the clean core concept, a 14% increase (ASUG Research and smartShift, year not stated).
• Under a fifth of the 2026 ASUG respondents say they are significantly optimized, while another 40% are somewhat optimized, but their Clean Core practices are not consistently applied (ASUG Research Report, 2026).
• SAP's framework sorts extensions into levels A through D. Level A is extend with SAP Build, either side-by-side or on stack, and Level C accesses internal objects (SAP Developer News, August 2025).
• SAP has said its earlier binary model of clean versus not clean was too restrictive and not applicable for systems with a lot of existing custom code developed with classic ABAP (SAP ABAP Extensibility Guide, August 2025). Practitioners should expect the level-based scoring to replace the older pass or fail view in SAP tooling.

Cost, timeline and failure risk

• Research from ISG, reported by The Register in February 2026, found nearly 60% of SAP migration projects delayed and over budget, with underestimated complexity and scope expansion as leading causes (Datapace, citing ISG, 2026).
• The same ISG research found that fewer than one in five organizations reimplement their processes when they move, and nearly half carry out little or no re-engineering (Datapace, citing ISG, 2026).
• A 2025 Horvath study of 200 SAP customers found only 8 percent finished on time, with projects running about 30 percent longer than planned (Thinklytics, citing Horvath, 2025).
• Gartner projects that, through 2027, 50% of organizations migrating to S/4HANA will underestimate the impact of custom code remediation on project timelines by at least 30% (ITChamps, citing Gartner, 2026). We did not locate the original Gartner note.
• Gartner, as reported by CIO, puts migration costs from a couple of million dollars to as much as a billion for the largest, most heavily customised installations (Assima, citing Gartner via CIO).

Testing and quality

• In the ASUG and Precisely study, the top-ranked challenge is process complexity: process complexity (62%), the top-ranked challenge, surpassing integration as the primary obstacle for this year (Precisely and ASUG, 2025).
• Integration with other systems of record is the next challenge at 49%, and understanding and defining process requirements (49%) is third (Precisely and ASUG, 2025).
• Horvath's analysis names underestimated testing and data migration as the main causes of overruns (Thinklytics, citing Horvath, 2025).
• Among SAPinsider's 2025 migration respondents (170 members), the tools used most often were 50% SAP Readiness Check, 43% ETL tools and 42% integration tools (SAPinsider 2025 benchmark, as summarized by LeverX).

Source: LeverX, summarizing SAPinsider 2025 S/4HANA Migration benchmark, 170 respondents

Custom code remediation: the disputed cause

Two widely cited figures attribute the top technical problem to custom code, and they do not agree.

• A 2024 SAP and IDG study, as cited by ITChamps, found 58% of IT leaders cite custom code remediation as their single largest technical hurdle in S/4HANA migrations (ITChamps, citing SAP/IDG, 2024).
• A separate ITChamps article attributes approximately 70% of organisations cite custom code adaptation as the single largest hurdle in S/4HANA migration to SAPinsider research (ITChamps, citing SAPinsider, 2026). We did not locate the original SAPinsider figure, and the number differs from the SAP/IDG figure. Use the range, not either number alone.

Measured results from clean core programs

Most of the results below come from SAP's showcase blog or from vendor-commissioned studies. Treat them as best-case figures from named customers, not averages.

• SAP's measurement framework cites Accenture, which has been able to remove 21% of the custom code from its core SAP applications within just six months (SAP, 2026).
• The same SAP post reports that Hitachi High-Tech archived 94% reduction of customization footprint (SAP, 2026).
• A Forrester Total Economic Impact study, commissioned by smartShift and based on five interviews, modeled a composite organization and reported a 254% ROI and $10.5 million in net present value over three years (Forrester TEI for smartShift, October 2026). This is vendor-commissioned.
• In the same study, the composite organization retired 25% of its custom code as unused or redundant, saving $3.5 million in maintenance and support (smartShift press release, October 2026).
• SAVIC, a consultancy, says clients with clean-core implementations consistently report 25–35% lower annual AMS costs (SAVIC, 2026). The method and sample are not disclosed.

Source: SAP, 2026; smartShift and Forrester TEI, October 2026. The three bars measure different things and should not be compared directly.

AI and the clean core

• On SAP's Q3 2026 earnings call, CEO Christian Klein said AI was the main driver behind our customers' move to the cloud in the quarter (Investing.com transcript, October 2026).
• In the SAPinsider survey, AI announcements outranked the maintenance deadline as the leading external factor (SAPinsider, 2026). We have no sourced figure that links clean core status to AI results, so we do not state one.

SAP's financial signals

• SAP reported Q3 2026 cloud revenue of €6.668 billion, up 26% year over year, or 25% at constant currencies (SAP Quarterly Statement Q3 2026).
• Cloud ERP Suite revenue rose 29% (28% at constant currencies) in the same quarter (SAP Quarterly Statement Q3 2026, PDF).
• Software support revenue fell 5% to €2.434 billion (SAP Quarterly Statement Q3 2026). SAP also said that the constant currencies software support revenue decline rate is expected to accelerate in the coming years as a consequence of an acceleration of customers transforming to the cloud (SAP investor relations, October 2026).
• SAP attributed part of the cloud growth to a one-off effect. Cloud growth benefited from quarter-specific effects, mainly a multi-quarter revenue catch-up from customers returning from financial distress (SAP Quarterly Statement Q3 2026).

Source: SAP Q3 2026 earnings call transcript, October 2026

What this means for your sign-off

• Measure before you estimate. Pull usage data first. Published unused-code shares range from roughly 20% to 75%, so an estimate built on an industry average is not a plan. Use the usage data for your own system to set the retire, remediate and redesign counts, then sign off on the actual numbers.
• Test the retirement decisions, not just the survivors. If retired objects are removed through a deletion transport, your regression scope and your evidence need to show that nothing live depended on them. Our phase-by-phase ECC to S/4HANA testing plan shows where that evidence fits.
• Plan for the process side, not just the code. The ASUG and Precisely figures put process complexity at the top of the challenge list, ahead of technical adaptation. Budget business-owner time for requirements and fit-to-standard decisions, not only for ABAP remediation.
• Treat clean core as an ongoing control. Only 17% of the ASUG respondents report significant optimization, so most landscapes will need governance after go-live. Our guide to S/4HANA upgrades and clean core regression covers how to keep the core clean once you are live.
• Use the templates. Our template library includes an S/4HANA migration readiness checklist and a regression plan you can adapt to your scope decisions.
• Keep AI on the agenda, but do not assume it removes the work. Organizations now rank AI above the 2027 deadline as a driver. Our practitioner's view of SAP AI covers what that means for test scope.

Frequently asked questions

How much SAP custom code is unused?

Published estimates vary widely. The SAP PRESS author cited above puts the never-called share at 60% to 75% (SAP PRESS, roughly three years old), while other vendor sources report lower ranges. Measure your own system rather than adopting any single figure.

What share of SAP customers expect to keep custom code after S/4HANA?

In the 2026 ASUG study of 168 members, ninety-two percent of respondents expect to carry custom code into SAP S/4HANA (ASUG Research Report, 2026).

How many organizations have completed an S/4HANA transition?

In SAPinsider's 2026 benchmark, 55% of companies report having deployed SAP S/4HANA, but only 34% indicate a complete transition (SAPinsider, 2026).

How often do S/4HANA migrations finish late or over budget?

ISG research reported in February 2026 found nearly 60% of SAP migration projects delayed and over budget (Datapace, citing ISG, 2026). A 2025 Horvath study found only 8% finished on time (Thinklytics, citing Horvath, 2025).

How many organizations are significantly optimized for clean core?

Only 17% of the 2026 ASUG respondents say they are significantly optimized (ASUG Research Report, 2026).

Does clean core reduce cost?

The best-documented figures are customer or vendor-commissioned. Accenture reported removing 21% of the custom code within six months (SAP, 2026). A Forrester study commissioned by smartShift reported a 254% ROI for a composite organization (Forrester TEI for smartShift, 2026).

Sources

1. SAPinsider Benchmark Research: ERP Migration and Transformation 2026, SAPinsider, 2026
2. 5 Hard Truths About the 2026 SAP ERP Migration Landscape, SAPinsider, 2026
3. New Research Reveals SAP S/4HANA Migration Momentum, Precisely and ASUG, November 2025
4. 2026 ASUG Research Report, ASUG Research hosted by smartShift, 2026
5. ASUG Research and smartShift Present Decoding SAP Clean Core, ASUG and smartShift, year not stated
6. Clean Core Measurement Framework: Track Your RISE with SAP Progress, SAP, 2026
7. How to Evaluate Custom Code Usage Data Ahead of An SAP S/4HANA Migration, SAP PRESS, undated
8. Custom Code Migration End-to-End How-to Guide, SAP Help Portal, 2023 edition
9. How to Extend SAP S/4HANA Cloud the Right Way, SAP News Center, August 2025
10. SAP Developer News, August 21st, 2025, SAP Community, 2025
11. ABAP Extensibility Guide: Clean Core for SAP S/4HANA Cloud, August 2025 Update, SAP Community, 2025
12. Why you should keep your core clean and how you can do it, SAP, 2022
13. SAP Quarterly Statement Q3 2026, SAP SE, October 2026
14. SAP Recent Results: Q3 2026 Financial Results, SAP Investor Relations, October 2026
15. SAP Quarterly Statement Q3 2026 (summary), Stocktitan reproduction of SAP filing, October 2026
16. Earnings call transcript: SAP tops Q3 2026 estimates, Investing.com, October 2026
17. ERP data migration: 55% deployed, 34% done, 16 months left, Datapace, 2026
18. The SAP S/4HANA 2027 Deadline: Don't Rush the Move, Assima, 2026, citing Gartner via CIO
19. How Long Does an SAP S/4HANA Migration Take?, Thinklytics, 2026, citing Horvath 2025
20. SAP ECC Custom Code Remediation for S/4HANA Migration, ITChamps, 2026, citing SAP/IDG 2024 and Gartner
21. SAP Customisation in S/4HANA: The 2026 Guide to Clean Core, ITChamps, 2026
22. Why SAP S/4HANA Migration in 2026 Is a Business Decision, LeverX, 2026, summarizing SAPinsider 2025
23. Why 2026 is the Make-or-Break Year for SAP S/4HANA Migration, Pinnacle Consulting, 2026
24. Total Economic Impact Study Finds smartShift SAP Custom Code Transformation Delivered 254% ROI, smartShift via GlobeNewswire, October 2026
25. Forrester Total Economic Impact study for smartShift, Forrester Consulting (commissioned), October 2026
26. SAP Clean Core Strategy 2026: Practical Guide for Enterprises, SAVIC, 2026
27. SAP ABAP Custom Code Remediation: Preparing for S/4HANA Compatibility, TotalTek, undated
28. Custom code: The burdened legacy of the SAP ECC era, e3mag, undated
29. SAP Clean Core Strategy 2026, Axxis Consulting, 2026
30. The Boring Enterprise Nerdletter #96, March 2026

Last updated: October 30, 2026. Statistics are refreshed as new research is published.