For ZF suppliers
Selected by ZF for the green electricity audit?
We check your green electricity share against your ZF commitment, and we know the ZF process.
No obligation, 45 minutes
- Audit firm (Wirtschaftsprüfungsgesellschaft)
- Big Four background
The essentials at a glance
- Due for 2026
- 31 May 2027
- Indicative fee
- €3,000 to €6,500, By scope and audit approach
Plus VAT, ±10 %, 2026; billed by time.
- How it works
- Remote, in three steps
- Audit language
- German or English
ZF suppliers worldwide have already relied on our support to prove their commitment. Remotely.
Germany
Italy
Türkiye
China
India
Poland
Czechia
Belgium
France
Spain
Switzerland
Hungary
Mexico
United States
Hong Kong
Who does your audit
Jannik Hassel, German Public Accountant (Wirtschaftsprüfer), justReporting GmbH Wirtschaftsprüfungsgesellschaft
Registered with the Chamber of Public Accountants (WPK) (opens in a new tab)Member of the Institute of Public Auditors (IDW) (opens in a new tab)
Audit programme developed with ZF (opens in a new tab)
- Trained at the Big Four
“[…] The whole process was very well structured, questions were answered quickly and competently, and we always felt securely guided through the audit. […]”
“We have had very good experiences working with justReporting. The audits were very thorough, reliable, fair and efficient.”
Step 2: to the engagement
How we get to the engagement
- PDF
Preliminary quote
XLSXDocument list
Request a quote
You receive: Preliminary quote, Document list
3 questions in the navigator Send the documents
Register extract etc.Quick alignment
15 minutes- PDF
Engagement letter
Sign the engagement letter
You receive: Engagement letter
Authorised signatory
Step 3: the audit
How the audit runs
Fully online.
Mainly a document review. Findings, no audit opinion. Enough for ZF.
- Now
Understand your set-up, gather what exists
What happens
- Calls on how you buy electricity
- We agree which evidence you still obtain
What you can prepare
- Electricity contracts
- Electricity invoices
- Consumption per site
- After year end
Check the final figures
What happens
- We go through the annual figures online
- We match figures with invoices and evidence
What you can prepare
- Annual consumption per site
- Your green electricity share calculation
- Evidence still missing
- By 31 May of the following year
Report and upload
What happens
- You receive the report with our findings
- We help you fill in the ZF declaration
What you can prepare
- Management confirms you gave us everything
- Upload report and declaration to SupplyOn
Already now: your first audit document
How the calculator works
- Choose how you assign electricity to ZF: whole consumption, mass balance or own meter.
- Enter the figures per site; the example clears when you click a field. Add as many sites as you need.
- The result shows your green share against your ZF commitment. Nothing is sent.
Work out your green electricity share now
The result is your first audit document: an Excel file with every formula, ready to keep working on.
| Step | Figures |
|---|---|
| Consumption in scope | |
| Whole consumption in scope, reporting yearGroup, entity or plants named in your ZF agreement, including electricity you generate and use yourself. | MWh |
| Green electricity | |
| Generated and used yourself, such as solarWith the installation's readings. Do not count it twice. | MWh |
| Retired certificatesGuarantees of origin, I-RECs or GECs of the reporting year, also via green tariff or PPA. Plant scope: the retirement note names the plant. Group or entity: no purpose needed. 1 certificate = 1 MWh. | MWh |
| Proven green electricity | 800MWh |
Help beside the audit
If you need other help
We handle the audit. For anything else, ask these two.
What ZF suppliers ask in the first call
Which certificates do we need, and where do we get them?
The certificate depends on where you use the electricity, such as guarantees of origin (GoO) in Europe or GECs in China. Electricity and evidence come together through own generation, a power purchase agreement (PPA) or a green tariff; or you buy certificates separately. They must be cancelled in your name; if only the ZF share is checked, the cancellation also names ZF parts production as its purpose. ZF works with ACT Commodities on green electricity purchasing; suppliers get support there with certificates and PPAs. We do not sell certificates.
Which documents do we have to prepare?
Mostly what you already have: your commitment from SupplyOn, the power bills and supply contracts of the reporting year, and the cancellation statements. Checking only the ZF share adds a separate meter's readings, or ZF and total revenue for a mass balance. You get your full list with the calculator or in the call. If something is missing, that is normal and no reason to wait.
What does the audit cost, and who pays?
Your company pays, not ZF. Indicative fee, reporting year 2026: about €3,000 to €6,500 per legal entity plus VAT, depending on scope and audit approach. We bill by actual effort, at the same rates for every ZF supplier; this is not a fixed price. Certificates you still need to buy come on top. The navigator shows your cost indication; through its form your purchasing team receives a written quote with scope, standard and fee.
By when do we have to be done?
Once ZF has selected you, the audit report and the signed ZF declaration are due in SupplyOn by 31 May of the following year, so by 31 May 2027 for reporting year 2026. In Germany, energy suppliers usually issue cancellation statements between January and March. We recommend clarifying the engagement right after the selection.
Does our own solar power or our green tariff count?
Yes, if you can prove it. You prove own generation with meter readings and a green tariff with your energy supplier's cancellation statement. If certificates were issued for your plant and sold, that electricity no longer counts for you. How own generation counts when only the ZF share is checked, we clarify in the call.
How is our ZF share calculated?
If only the ZF share is checked and ZF production has no dedicated meter, the share is calculated: ZF revenue divided by the site's total revenue, times total consumption. Of that, you prove the share you committed. The weight of goods delivered can be used instead of revenue. With the calculator you estimate your share yourself beforehand.
Why is our energy supplier's certificate not enough?
It shows that green electricity was supplied or cancelled. An independent auditor checks that the cancelled certificates cover your consumption or the ZF share and are claimed by nobody else. That matters because your green electricity feeds into the carbon footprint of ZF parts and ZF's Scope 3 emissions.
Will ZF see our revenue and consumption figures?
Not from us. You are our client, not ZF, and we pass neither revenue nor electricity data on to ZF. ZF sees what you upload to SupplyOn yourself: the audit report and the ZF declaration. You see both before you upload them. We reach our conclusion independently. Confidentiality is a professional duty (section 43 WPO, section 203 StGB).
Can we postpone the audit, and what if we miss the deadline?
Whether the audit can be postponed is ZF's decision, not ours. Without a timely upload you count as non-compliant with ZF. If time gets short, contact ZF early at sustainability.supplychain@zf.com. In the call we work out what is feasible by the deadline.
Can we appoint a different auditor?
Yes. You decide whom you appoint. The audit can be done by an independent public accountant or a registered audit firm. You can still put your questions to us.
Intro call, no cost
Book the call now and get your audit under way
No obligation, in English or German. Afterwards you have:
- Scope and audit approach for your case
- Your document list
- Your cost indication
- On request, a written offer for your purchasing team

You speak with Jannik Hassel, German Public Accountant (Wirtschaftsprüfer).On Microsoft Teams.
Prefer e-mail or phone?
A reply to every e-mail within 48 hours on working days. If it is urgent, say so and we will answer as soon as we can.