TÜV Austria Certification: What the Numbers on Our Certificates Mean
TL;DR — Five things every procurement officer needs to know about a TÜV Austria OK Compost certificate:
- The certificate number is structured as TA + 6 digits + control letter (e.g., TA801180N), where the 6-digit suffix is the unique certificate ID and the final letter is a checksum — not a product code.
- OK Compost certification requires passing four independent tests per EN 13432: chemical characterisation, biodegradation (≥90% in 6 months), disintegration (≥90% in 12 weeks at 2 mm mesh), and ecotoxicity (no negative effect on plant growth).
- OK Compost, OK Compost HOME, and OK Biodegradable WATER are three different certifications — most buyers mistake OK Compost for "compostable at home" when it actually means industrial composting at 58°C.
- Heavy metals must be below 50 mg/kg combined (Pb+Hg+Cd+Cr⁶) per EN 13432 — many self-declared "biodegradable" films exceed this threshold quietly.
- Each certificate is tied to a specific production line AND a specific material formulation — a new additive or a new supplier of pulp can invalidate the certification, which is why TÜV Austria audits annually.
I get the same question almost every week from a sustainability lead somewhere in Europe: "You say your film is OK Compost certified. Can you send me the certificate?" I send it. They look at the PDF, see a string of numbers and a logo, and reply with a more confused version of the same question — "What does TA801180N actually mean? Is this the same as home compostable?" The honest answer is that nine out of ten buyers cannot read a TÜV Austria certificate, and most suppliers will not explain it because because they themselves have not read the certificate carefully enough to know which of their SKUs are covered and which are not.
This article is the document I wish every sustainability lead had on their desk before the next supplier audit. We will decode the certificate number field by field, walk through the four EN 13432 tests that earn a material the right to carry the OK Compost mark, distinguish the three TÜV Austria marks that are routinely conflated in marketing copy, and explain how to verify a supplier's certificate without ever picking up the phone. We will treat the TÜV Austria OK Compost database as the source of truth, because that is what it is.
Why I Spend Time Reading Other People's Certificates (And You Should Too)
A Frankfurt call from 2024
In late 2024 a sustainability lead at a Frankfurt-based private-label food company sent me a competitor's certificate to ask "is this what your certificate looks like?" It was. The certificate number followed the standard format, the auditee was the right company, and the mark was OK Compost. What was wrong was everything around it: because the certificate was issued for a 100% cellulose substrate, but the film the supplier was actually shipping was a 30% bio-based PLA blend, the certificate was not valid for the product in the box. The Frankfurt team had been quoting an OK Compost number in their sustainability report for nine months that did not cover the material they were actually shipping.
What the certificate number is not
I tell every procurement officer the same thing: because the certificate number is assigned to a specific formulation on a specific production line, the number is not a generic badge that travels with the brand — it is a passport that belongs to one exact recipe. Change the recipe and the passport is invalid. The number does not tell you the SKU, the country of origin, the substrate weight, or the adhesive chemistry. Those details live in the certificate body, not the ID, and you have to read them to know what is actually covered.
That is why I read other people's certificates, and why you should too. The certificate is the only document that proves the claim on the product brochure is real, and the only way to know whether the claim is real is to read the document.
The TÜV Austria Certificate Number, Field by Field: Decoding TA801180N and Beyond
Every TÜV Austria OK Compost certificate number follows the same structural format: two issuer letters, six numeric digits, and one alphabetical control letter. The example TA801180N breaks down as follows.
| Position | Characters | Meaning | Example (TA801180N) |
|---|---|---|---|
| Issuer | TA (2 letters) | Certifying body — TÜV Austria | TA |
| Certificate ID | 6 digits | Unique sequential identifier assigned to the formulation, production line, and auditee | 801180 |
| Checksum | 1 letter | Internal verification character — not a product code, grade, or revision marker | N |
Three things this ID does not tell you, and where to find them instead:
- What the product is. The certificate body lists the material formulation, the substrate, the adhesive (if applicable), and any inks or coatings. You have to read the body to know what the certificate covers.
- Who the auditee is. The auditee is the company whose production line was audited. A supplier brand may hold multiple certificates across multiple auditee entities, and the brand name on the certificate may not match the brand on the product datasheet.
- Whether the certificate is current. The validity dates are in the certificate body. The certificate ID alone does not tell you whether the certificate is active, suspended, or expired — you need to cross-check the live TÜV Austria database to confirm.
Because the ID is a passport for one exact recipe, the smart procurement move is to build a supplier-side registry of certificate IDs mapped to SKU codes — and to require suppliers to flag any SKU whose certificate ID is not in the registry. That one registry has saved more compliance errors than any audit I have ever run.
The Four Tests Behind OK Compost — And Why Each One Can Independently Fail a Submission
The OK Compost mark is not a self-declared sustainability badge — it is a pass-fail result from four independent laboratory tests, and any one of them can fail a submission on its own. This is the single most important fact about the certification, and it is the one most overlooked in marketing copy.
| Test | Standard reference | Threshold | What it catches |
|---|---|---|---|
| Chemical characterisation | EN 13432 §4.1 | Pb < 100 mg/kg, Hg < 0.5 mg/kg, Cd < 0.5 mg/kg, Cr⁶ < 0.5 mg/kg; combined ≤ 50 mg/kg | Heavy metals and regulated substances |
| Biodegradation | OECD 301B (modified Sturm) | ≥90% conversion to CO₂ in 6 months under controlled composting | Materials that fragment but never mineralise |
| Disintegration | EN 13432 §4.3 | ≥90% of sample passes through 2 mm mesh within 12 weeks at 58°C, 65% RH | Materials that biodegrade slowly but are visible as fragments |
| Ecotoxicity | OECD 208 (plant growth) | No negative effect on germination and biomass vs control compost | Residual chemicals that harm plant growth |
Let me make each test concrete, because the threshold is the part that gets papered over in brochure claims.
Test 1 — Chemical characterisation
The first test is the cheapest and the easiest to fail. Because the heavy metals threshold is per dry mass, a single contaminated pigment in a coloured film can tip the combined total above 50 mg/kg and disqualify the entire submission. At Zhejiang Xiade New Material Co., Ltd. we hold this threshold by sourcing all pigments from suppliers who provide lot-traceable heavy-metals certificates, and we re-test every batch.
Test 2 — Biodegradation (OECD 301B)
The second test is the slowest. Because the test runs for 180 days and measures CO₂ evolution from microbial metabolism, a material that fragments but does not mineralise — oxo-degradable plastics, for example — fails this test dramatically, often below 30% conversion. Regenerated cellulose, by contrast, typically delivers 95–98% conversion within the 6-month window.
Test 3 — Disintegration
The third test is the most visually striking. Because the test sieves the composted sample through a 2 mm mesh after 12 weeks, any material that disappears at the molecular level but leaves visible fragments above 2 mm fails this test independently. This is the test that catches formulations with high biopolymer content but poor dispersion in the compost matrix.
Test 4 — Ecotoxicity (OECD 208)
The fourth test is the easiest to underestimate. Because the test plants seeds in composted sample material and compares germination rate and biomass against a control, residual additives that do not show up in the chemical characterisation step can still suppress plant growth. I have seen this test fail on formulations that passed all three prior tests, because the plasticiser additive was mildly phytotoxic at the residual level.
Because each test can fail independently, a supplier that claims "OK Compost certified" without naming the certificate number is making a claim that cannot be verified against any specific test result. Because the certificate number is the only document that proves the claim covers the entire four-test protocol, the certificate number is the claim.
OK Compost, OK Compost HOME, OK Biodegradable WATER: Which Mark You Actually Need
Three TÜV Austria marks are routinely conflated in marketing copy, and the conflation has real consequences for buyers who ship into different end-of-life scenarios.
| Mark | End-of-life scenario | Test conditions | Typical use case |
|---|---|---|---|
| OK Compost (Industrial) | Municipal or commercial composting facility | 58°C, 65% RH, 12 weeks, 2 mm mesh | Foodservice packaging, bagasse containers, certified compostable films |
| OK Compost HOME | Backyard compost bin | 20–30°C ambient, lower microbial activity, longer duration | Home gardening bags, household compostable films, tea bags |
| OK Biodegradable WATER | Freshwater biodegradation | ASTM D6691 / OECD 301B modified for freshwater | Marine-adjacent applications, fishing gear, water-soluble sachets |
The most common mistake I see is a buyer specifying "OK Compost" for a product that ends up in a backyard compost bin in the consumer's garden. Because industrial composting conditions (58°C, 65% RH) do not exist in a backyard bin, an OK Compost-certified material will not break down at a meaningful rate in a home compost pile — it will sit there for years looking identical to the day it was buried. The OK Compost HOME mark is significantly more demanding on the formulation because the microbial activity at 20–30°C is much lower, and not every OK Compost formulation passes the HOME test.
For EU procurement officers, the right question is not "do you have an OK Compost mark?" but "which OK Compost mark, and what is the certificate number?" Because the three marks are non-interchangeable, a single OK Compost certificate is not a substitute for OK Compost HOME certification when the product's real end-of-life pathway is the household bin.
The Audit Trail: How TÜV Austria Confirms Our Line Numbers Year After Year
OK Compost certification is not a one-time pass — it is an annual on-site audit that re-tests the material, audits the production line, and re-issues the certificate with a new audit date. This is the audit trail that most buyers never see, and it is the audit trail that distinguishes a real certification from a static marketing badge.
At Zhejiang Xiade New Material Co., Ltd., the audit cycle runs roughly as follows. TÜV Austria issues the initial certificate after the four-test submission passes. The certificate is then valid for 12 months, conditional on annual re-audit. During the re-audit, TÜV Austria inspectors visit our 116,700 sqm facility in Zhejiang, take line samples, re-test the four EN 13432 thresholds, audit the raw material supply chain (especially pulp and adhesive suppliers), and review any reformulation since the prior audit. If everything passes, the certificate is renewed. If there is a reformulation, we have to submit a new four-test report before the renewal is granted.
Because the audit trail is annual, a certificate that has not been re-audited in 12 months is at risk of suspension, and a certificate that has been re-audited but does not appear in the live TÜV Austria database is not valid regardless of what the PDF says. This is the check most procurement audits skip, and it is the check that catches the most falsified or expired claims.
How to Read a Supplier's Certificate Without Calling Their Sales Team
The fastest way to verify a TÜV Austria OK Compost certificate is a 5-minute workflow that does not require the supplier to be on the phone. The protocol below is the one I share with every B2B procurement team that asks.
- Pull the certificate PDF and the certificate number. The certificate number follows the format TA + 6 digits + control letter. Note the auditee company name, the certified material description, and the validity dates.
- Cross-check against the live TÜV Austria database. Search the certificate number in the database. Verify the auditee, the formulation, and the current validity status. If the number does not appear, the certificate is not valid.
- Match the SKU to the certified formulation. Request the supplier's product SKU list mapped to the certified formulation. A supplier may hold multiple OK Compost certificates for different SKUs — a single certificate does not cover the entire catalogue.
- Verify the audit date is within 12 months. Check the last TÜV Austria audit date. If the last audit is more than 12 months old, the certificate is at risk of suspension pending re-audit. Ask the supplier for the most recent audit confirmation letter.
- Check for scope changes since the last audit. Ask the supplier whether any reformulation, raw material supplier change, or process change has occurred since the last audit. Any scope change requires re-submission to TÜV Austria, and the certificate is invalid until the new submission is approved.
The bottom line is this: because the certificate number is the only document that proves the OK Compost claim is real, current, and tied to a specific formulation, the certificate number is the only ESG metric on the supplier datasheet that actually needs to be checked. Everything else — the mark, the brochure, the salesperson's assurance — is decoration. The number is the substance.
Request the full TÜV Austria certificate dossier for our cellulose film line
We supply the complete certificate PDF, the auditee record, the annual audit date, and the SKU-to-formulation mapping on request. For procurement teams verifying multiple suppliers, we also supply a side-by-side comparison sheet templated to your internal audit checklist.
→ About XIADE — certifications & facility
→ Cellulose film product family
→ Request the certificate dossier & quote
Frequently Asked Questions
What does the OK Compost mark mean on packaging?
The OK Compost mark issued by TÜV Austria means the material has passed all four EN 13432 tests: chemical characterisation (heavy metals below 50 mg/kg combined), biodegradation (≥90% in 6 months under OECD 301B), disintegration (≥90% in 12 weeks at 2 mm mesh in industrial composting at 58°C and 65% RH), and ecotoxicity (no negative effect on plant growth per OECD 208). The mark is not equivalent to home composting — for that you need the separate OK Compost HOME mark.
How do I read a TÜV Austria certificate number?
TÜV Austria certificate numbers follow the format TA + 6 digits + control letter (e.g., TA801180N). The TA prefix identifies TÜV Austria as the certifying body. The 6-digit suffix is the unique certificate ID assigned to the specific material formulation, production line, and auditee. The final letter is a checksum and is not a product code or grade designation.
What is the difference between OK Compost and OK Compost HOME?
OK Compost tests for industrial composting at 58°C and 65% RH — the conditions inside a municipal or commercial composting facility. OK Compost HOME tests for disintegration at ambient household temperatures of 20–30°C, which is significantly more demanding because lower temperatures slow microbial activity. A material with OK Compost but not OK Compost HOME will not break down in a backyard compost bin at a meaningful rate.
How do I verify a supplier's TÜV Austria certificate is current?
You can verify a TÜV Austria certificate against the live TÜV Austria database at https://www.tuv-at.at/green-mark/certifications/ by searching the certificate number. The database shows the current validity status, the auditee company name, the certified material formulation, and the approval date. If the supplier's certificate number does not appear in the database, the certificate is not valid. Do not rely on a PDF alone — always cross-check.
Does OK Compost certification cover the adhesive layer of a tape or laminate?
Yes — but only if the adhesive is part of the submitted and certified composition. TÜV Austria tests the material as a whole, including the substrate, the adhesive, and any coatings or inks. A film substrate with OK Compost certification does not mean a tape product incorporating that film is automatically certified — the tape must be tested as a finished article. This is one of the most common compliance errors in the marketplace.
What heavy metal thresholds does EN 13432 set?
Per EN 13432, the combined concentration of lead (Pb), mercury (Hg), cadmium (Cd), and hexavalent chromium (Cr⁶) must be below 50 mg/kg of dry mass, with individual limits of Pb < 100 mg/kg, Hg < 0.5 mg/kg, Cd < 0.5 mg/kg, and Cr⁶ < 0.5 mg/kg for some formulations. Materials exceeding any of these thresholds fail the chemical characterisation step and are not eligible for the OK Compost mark.
How often does TÜV Austria re-audit certified products?
TÜV Austria performs annual on-site audits of certified production lines, including reformulation review, raw material traceability, and finished-product testing. A new additive, a new pulp supplier, or a process change requires re-submission before the certificate is updated. A certificate that has not been audited in over 12 months is at risk of suspension and should be flagged in any supplier audit.
Is OK Compost certification accepted in the US and Asia?
OK Compost certification is widely accepted in the EU as equivalent to EN 13432 compliance. In the US, ASTM D6400 is the parallel standard and is not interchangeable with OK Compost — a separate ASTM D6400 submission is required for US market claims. In Asia, markets such as Japan, Korea, and Singapore have local standards (e.g., GreenPla in Japan) that may require additional certification. For global B2B buyers, EN 13432 + ASTM D6400 + regional certification is the safest combination.