Why Phase 0 Is Where SAP Programmes Are Won or Lost

Mar 18, 2026

finance
IT
SAP

How early decisions shape every outcome in your SAP journey.

Across the ERP market, independent studies continue to put material under-performance above the 50 percent mark. Many programmes exceed original budgets by 30 to 50 percent. In more troubled cases, overruns move beyond 100 percent and timelines extend by 20 to 30 percent. Those outcomes rarely originate in build. They are set in motion before design workshops begin.

As the SAP ECC support deadline rapidly approaches, the pressure on ECC customers to modernise and move to SAP’s next generation S/4HANA ERP is building. These companies are steadily taking the plunge and embarking on their S/4HANA ERP modernisation journey.

Phase 0 is the first step of the S/4HANA journey and getting it right up front is the biggest driver for success. Phase 0 is the point at which you still have leverage. It is the only stage where clarity is inexpensive.

Key takeaways

Most structural SAP risk is introduced before build starts.
Phase 0 is a decision window with defined outputs, not a pre-sales exercise.
Scope, governance, operating model and BAU ownership must be explicit before mobilisation.
A disciplined Phase 0 reduces the probability and scale of cost and timeline overruns.
Strong setup lowers friction in UAT, cutover and hypercare.

What is Phase 0?

Phase 0 is a foundational assessment phase focused on defining the transformation scope, migration approach, business case and roadmap BEFORE commencing your S/4HANA implementation. It provides the opportunity to take a step back and address the Big Rock / No-regret decisions that will ensure successful delivery of your programme – establishing clear objectives, realistic budgets, and aligned expectations across business and IT.

Why Phase 0 Gets Compressed

Phase 0 often feels like something that can be accelerated. Leadership wants momentum. Partners want to mobilise. There is pressure to publish dates and budgets early.

Teams assemble. Design workshops begin. Starting build creates visible activity. It looks like progress.

The difficulty is that many of the foundational decisions remain unsettled. Scope boundaries are implied rather than agreed. Standardisation principles are discussed but not tested. Operating model implications are deferred. Governance forums are named but not empowered.

Industry research consistently traces ERP failure back to weak upfront planning, unstable scope and misaligned sponsorship. When more than half of programmes miss original objectives, it is rarely because configuration was technically impossible. It is because leadership alignment and scope discipline were never locked down.

If Phase 0 is compressed, the work still happens. It simply happens later, under delivery pressure, when commercial and reputational cost is higher.

What Phase 0 is actually solving

In many SAP programmes, ambition moves faster than definition.

The conversation moves quickly to solution architecture, system integrators and indicative budgets. Indicative delivery timelines take shape. Steering committees form. Meanwhile, basic questions remain open:

Are we aligned on programme principles, scope and expected outcomes
Do we understand our starting point and are we aligned on the target state
Are Business and IT aligned on the ERP migration approach
Are we confident with the delivery timelines / budget and has this been thoroughly tested against the agreed scope
What success looks like in measurable terms.
Do we have a clearly defined scope for Phase one (e.g., Which entities, products, geographies, integrations, etc. ) .
Where standard process will be mandated and where deviation is permitted.
Who owns end-to-end processes after go live.

In post-implementation reviews, the same themes repeat. Objectives were high level. Scope shifted. Executive sponsors held different mental models of what the programme was for. The operating model impact was underestimated.

Phase 0 forces the organisation to move from aspiration to definition. It makes leadership state, in practical terms, what is in and what is out.

Why delivery cannot repair a weak setup

There is a belief that structured build cycles will refine and stabilise scope as the programme progresses. In reality, build amplifies whatever it inherits.

If scope is loose, workshops become negotiations. If governance is unclear, decisions escalate repeatedly. If ownership is blurred, friction is attributed to the system.

Executives recognise the impact in numbers. Troubled ERP programmes often exceed budgets by 50 percent or more. Some research has cited average overruns in the high double digits, with extreme cases approaching 150 to 200 percent. Timelines stretch. Internal teams divert capacity to issue management rather than value delivery.

These are consequences of ambiguity entering the programme too early.

Once contracts are signed and teams mobilised, correcting that ambiguity becomes materially more expensive.

What a strong Phase 0 produces

A disciplined Phase 0 is structured and time-bound. Its purpose is to produce decisions that leadership will defend.

It typically delivers six concrete outcomes.

First, a business case with clarity of intent and value. The programme names the outcomes it will measure. That might mean reducing days to close by 30 to 40 percent, retiring a defined number of legacy platforms within 18 months, or removing a set percentage of manual reconciliations. Benefits are expressed in ranges and linked to ownership.

Second, clearly defined design guardrails and scope. Principles on standard versus custom are explicit. Tolerance for exception is controlled. Phase one process and functional coverage is stated in language business leaders recognise, for example record to report and procure to pay across named entities.
Third, a detailed assessment of ECC to S/4HANA migration options (i.e., greenfield, bluefield, brownfield) and a recommendation on the optimal migration approach / timeline / costs taking into account expected outcomes, scope and design guardrails.
Fourth, a high-level roadmap with bounded scope and sequencing. Phase one scope fits on a single page and can be tested against executive expectations. A high-level roadmap reflects regulatory deadlines, market events and internal capacity.
Fifth, a governance model with real decision rights. When time, cost and scope collide, it is clear who has the casting vote. Escalation paths and response expectations are defined before pressure builds.
Sixth, a programme delivery model for the implementation phase, with clear roles and responsibilities across internal and external resources. The organisation has a view on product ownership, internal capability, partner split and release management before go live is in sight.

These outputs create a baseline. When SAP Activate moves into Discover and Prepare, it does so with a shared frame of reference rather than an unresolved strategy debate.

Where Phase 0 pays back

The return on Phase 0 is visible later in several ways.

Scope challenges are resolved by reference to agreed priorities. Governance forums close decisions in one meeting rather than three. UAT surfaces defects and design gaps, not fundamental misunderstandings.

In risk terms, Phase 0 reduces the likelihood of becoming part of the majority that overrun. It also reduces the magnitude of overrun when change occurs, because there is a documented baseline against which trade-offs can be made. It does not eliminate complexity. It structures it.

Signs that Phase 0 has been rushed

There are predictable signals that setup has been underpowered.

Steering discussions fixate on budget and dates, yet no one can describe scope boundaries clearly. Executives describe the programme differently. The first go live footprint is fluid. Future SAP ownership is undefined beyond general statements. Integration dependencies are acknowledged but not sequenced.

Delivery may still start strongly. The risk simply moves underground and reappears later, often in design churn, change requests and extended hypercare.

Ambiguity compounds when left unmanaged.

Final perspective

Most SAP ERP programmes struggle because uncertainty was allowed into the programme before build began. Delivery then carries that uncertainty forward.

Phase 0 is the mechanism for removing it early, when options are wider and cost is lower.

Before a major SAP investment begins, leadership should be able to answer five questions: