The short answer. Mainstream maintenance for SAP ECC (EHP 6–8) ends on 31 December 2027, with optional extended maintenance to the end of 2030 at a premium. The deadline is not really about switching software. It is about whether your data is clean, complete, and ready to move, because that is what decides whether an S/4HANA migration lands on time or stalls.

If you run SAP ECC, you have almost certainly seen the 2027 date by now. It shows up in vendor emails, board slides, and analyst reports, usually framed as a countdown to a system upgrade. That framing is where a lot of programmes quietly go wrong.

The move to S/4HANA is a large undertaking, but the part that most often slips timelines is not the technical conversion. It is the data. This piece lays out what the deadline actually requires, why data readiness is the real test, what a data-ready migration looks like in practice, and how to use the time you have left well.

What the 2027 deadline actually is

First, the facts, because several dates circulate and the confusion is unhelpful. SAP has confirmed the following maintenance timeline for SAP ECC (SAP ERP 6.0):

ECC version	Mainstream maintenance ends	Extended maintenance
EHP 0–5	31 December 2025 (already passed)	Not offered
EHP 6–8	31 December 2027	Optional, to 31 December 2030, at a premium

The 2027 date is the one that applies to most SAP customers still on ECC. After it, systems on EHP 6–8 move into what SAP calls customer-specific maintenance unless extended maintenance is purchased. Extended maintenance carries an added cost, which SAP has described as around two percentage points on the maintenance base, and runs from the start of 2028 to the end of 2030. It keeps security and legal updates flowing, but it does not bring new features or full support.

For organisations on the older EHP 0–5 versions, the position is already more serious: mainstream maintenance for those ended at the close of 2025, with no extended-maintenance option, so those systems are already in customer-specific maintenance with reduced protection.

What your options actually are after 2027

Nothing switches off overnight in 2027. What changes is the level of protection, the cost of staying put, and the room to plan on your own terms. Broadly, an EHP 6–8 customer has three paths:

Migrate to S/4HANA before the deadline. The cleanest option, and the one that removes the maintenance question entirely, but it requires the data work to be done in time.
Buy extended maintenance to 2030. This buys time at a premium, but it is a bridge, not a destination. The migration still has to happen, and the clock simply moves to 2030.
Fall into customer-specific maintenance. The default if you do nothing. It costs the same as mainstream maintenance but delivers less: no new features, and over time, reduced legal and security updates. Risk accumulates quietly.

Whichever path you choose, the underlying work is the same. Extended maintenance does not remove the need to migrate; it only changes when. So the sensible planning assumption is that a migration is coming, and the only real variable is how prepared you are when you start it.

Why it is a data deadline, not a software deadline

Here is the part that gets lost. Moving to S/4HANA is not a copy-and-paste of your ECC system. S/4HANA uses a different data model. The clearest example is the Business Partner model, which replaces the separate customer and vendor records that ECC kept apart. Data that was acceptable in ECC often cannot move across as-is.

That means every migration has to answer some hard questions about the data itself, well before any cutover:

Is it clean? Duplicates, inconsistent formats, and incomplete records that were tolerated for years in ECC will block or corrupt a load into S/4HANA.
Is it complete? Mandatory fields in the new model may have been optional or empty in the old one.
Does it map? Company codes, account groups, and organisational structures have to be transformed to the target model, not just carried over.
Can you prove it? A migration is not done when data loads. It is done when you can reconcile it against the source and show it is accurate.

A migration programme rarely fails because the technology could not do the job. It stalls because the data was not ready for it.

This is why the deadline is deceptive. The software conversion is a known, well-tooled process with a large ecosystem of experience behind it. The data preparation is the open-ended part, and it is the part that expands to consume whatever time you did not plan for. Two organisations can buy the same tools and hire the same integrator, and the one with cleaner data will finish first, every time.

What "data-ready" actually looks like

Readiness is not a feeling or a status meeting. It is a set of checks that either pass or fail. A data-ready migration has worked through each of these before cutover:

Discovery and profiling. You know what data you have, where it lives, and where the quality problems are, backed by evidence rather than assumption.
Cleansing and de-duplication. Duplicate masters have been resolved into trusted records, so you are not carrying the same customer or material into S/4HANA five times over.
Transformation and mapping. Legacy structures are mapped to the S/4HANA model, including the move to Business Partner.
Validation and reconciliation. Loaded data is checked against the source, so counts and values match and nothing is silently lost.
Safe test data. Non-production environments used for testing hold realistic data with sensitive fields protected, so testing is both useful and compliant.

Notice that only one of these is really about the cutover itself. The rest is data work, and it is the work that decides the outcome. A useful way to sanity-check readiness is to ask, for any object you plan to migrate, whether you could produce evidence today of its completeness, its duplicate rate, and how it maps to the target. If the answer is no, that object is not ready, regardless of how confident the project plan looks.

The approach you choose depends on the data

S/4HANA migrations generally follow one of three approaches, and the right one for you depends partly on how clean your starting point is:

Greenfield is a fresh implementation. You redesign processes and bring across only the data that deserves to move, which makes it a natural moment for a thorough clean-up.
Brownfield is a system conversion that carries your existing setup forward. It is faster in principle, but it also carries existing data problems forward unless they are fixed first.
Bluefield, or selective data transition, sits in between: you keep what matters and leave the rest, which demands careful, selective data handling.

The common thread is that data quality shapes the decision. A landscape with clean, well-understood data has more options open to it. A landscape with years of accumulated duplicates and gaps often finds the choice made for it by the state of the data. Profiling early is what turns this from a guess into an informed decision.

How to use the time between now and 2027

Whether your target is 2027 or you plan to buy extended maintenance into 2030, the practical advice is the same: start the data work early, because it is the long pole. A sensible order of priorities:

Profile first, decide second. Understand the true state of your data before committing to a migration approach or a date. The findings often change the plan.
Fix master data now. Duplicate and inconsistent master data is the single biggest source of migration delay. It can be cleaned in parallel with everything else, so there is no reason to wait for the programme to formally start.
Choose the approach that fits the data. Let the profiling results inform whether Greenfield, Brownfield, or Bluefield is right, rather than deciding first and discovering the data problems later.
Treat reconciliation as a requirement, not a formality. Build in the ability to prove the migration was accurate from the very start, so go-live is a moment of confidence rather than hope.

The organisations that treat 2027 as a data programme with a technology event at the end, rather than a technology event with some data cleanup attached, are the ones that tend to finish calmly. The date is fixed. The readiness is the variable you control.

How deKorvai helps

deKorvai is a data platform built for exactly this work. For S/4HANA migrations, it runs as an end-to-end flow: extract from ECC, profile and validate, transform and map to the S/4HANA model, scramble sensitive data for non-production, then load into the Migration Cockpit (DMC or LTMC) staging tables with reconciliation built in. It supports Greenfield, Bluefield, and GROW programmes.

The point is that data quality, transformation, and validation are not separate tools stitched together at the last minute. They run on one platform, as one process, so readiness is continuous rather than a scramble before go-live. In one documented business partner migration, deKorvai moved more than 50,000 vendor records into DMC staging tables with 100% data accuracy and a 95%+ first-pass rate.

Key takeaways

The date: ECC mainstream maintenance (EHP 6–8) ends 31 December 2027; extended maintenance runs to 2030 at a premium.
The real test: S/4HANA uses a different data model, so migrations succeed or fail on data readiness, not on the technical conversion.
The long pole: data cleansing, transformation, and reconciliation take the most time, so start them early.
The advantage: running data quality and migration as one flow keeps readiness continuous instead of last-minute.

Frequently asked questions

When does SAP ECC support actually end?

Mainstream maintenance for SAP ECC on Enhancement Packages 6 to 8 ends on 31 December 2027. Older versions (EHP 0 to 5) already reached the end of mainstream maintenance on 31 December 2025.

What happens if I stay on ECC after 2027?

Without extended maintenance, systems move into customer-specific maintenance, which continues at a similar cost but without new features, and with reduced legal and security updates over time. Optional extended maintenance is available to the end of 2030 at a premium.

Does the deadline mean my system stops working?

No. ECC keeps running after 2027. What changes is the level of support and protection, the rising cost and risk of staying, and the shrinking window to plan a move on your own timeline.

Why is data the hard part of an S/4HANA migration?

S/4HANA uses a different data model, including the Business Partner model that replaces separate customer and vendor records. Legacy data usually cannot move across unchanged, so it has to be profiled, cleaned, transformed, and reconciled before it can load correctly.

How early should we start preparing data?

As early as possible. Data cleansing, transformation, and reconciliation are the longest and least predictable parts of a migration, so starting them early is the most reliable way to protect the timeline, whether your target is 2027 or 2030.

The SAP ECC 2027 Deadline: Why Your Migration Lives or Dies on Data