BDN and MGO Documentation Rules Buyers Must Follow in 2026

A vessel lifts marine gas oil in Rotterdam, and three weeks later a port state inspector in Lagos finds the BDN missing the density at 15°C field. The cargo is compliant. The quality is fine. The paperwork is not — and the ship is now in a compliance process that costs more than the fuel did.

This article sets out the BDN and MGO documentation rules buyers must follow in 2026: what the recent MARPOL Annex VI amendments did and did not change, what a compliant Bunker Delivery Note must contain, how ISO 8217:2024 and ISO 4259 frame quality acceptance, and the dispute-avoidance protocol a direct-origin supplier should operate so your cargo is never the one held at the dock.

What BDN rules apply to marine gas oil in 2026?

The MGO rules that bite in 2026 are not new rules: they are the Appendix V BDN content, the flashpoint entry added in 2024, and the long-standing retention duties, now applied by port state control with little tolerance for gaps.

Two recent amendments are worth separating. First, resolution MEPC.362(79), in force since 1 May 2024, requires the BDN to state the flashpoint of the fuel where it is below 70°C, or a statement that it was measured at or above 70°C. Second, resolution MEPC.385(81), in force since 1 August 2025, clarified the definition of fuel oil and extended BDN requirements to low-flashpoint fuels and gas fuels such as LNG and methanol. For a ship burning MGO, the 2025 change adds nothing to the note itself; it matters only if the same operator also bunkers alternative fuels.

The retention duties are unchanged: the BDN stays on board for three years after delivery, and the sealed representative sample stays under the ship's control until the fuel is substantially consumed, and in any case for not less than 12 months. For ships on the simple MGO rule — 0.10% sulfur inside emission control areas, 0.50% globally outside — the document has to prove what the product is, who supplied it, and that it meets the limit.

What exactly must a compliant Bunker Delivery Note contain?

A compliant BDN carries the Appendix V fields in full: ship and delivery details, supplier identity, product and quantity, density, sulfur, flashpoint, and a signed supplier declaration. The mandatory fields and the common practice around them:

Viscosity is not a mandatory BDN field, although it belongs on the certificate of quality. Most suppliers also record the representative sample's seal number on the BDN; that is good practice rather than an Appendix V field, and it makes the sample and the note reconcilable in seconds. A BDN with blanks in any mandatory field is a BDN that fails inspection.

How do ISO 8217:2024 and ISO 4259 govern quality acceptance?

ISO 8217:2024 sets the grade limits and general requirements for marine fuels, and ISO 4259 decides how a disputed test result is compared against those limits.

The current edition, ISO 8217:2024, was published in 2024 and replaced the 2017 edition. Its Clause 5 sets general requirements that apply to every grade — for example, that the fuel is free from inorganic acids, organic chlorides, and substances that make it unsafe or harmful. The distillate table, including DMA and DMZ for MGO, sets the property limits. Where a result sits close to a limit, the standard refers to ISO 4259, which uses each test method's reproducibility to decide whether the fuel is on or off specification. Three rules matter in practice:

• Specification governs: the contracted grade and edition, not generic expectations, decide acceptance. If you contracted ISO 8217:2024 DMA, those table limits and the general requirements are the line.
• Sample discipline: the sealed representative sample is the referee. Both sides sign it; disputes are tested against it at a mutually agreed laboratory.
• Precision, not a single number: under ISO 4259, one result marginally over a limit does not by itself prove off-spec fuel. Contracts that name the edition and the precision rule avoid arguments over decimals.

This is why a clean contract references the grade, the edition, the property limits, and the testing protocol in one place — and why port rejection usually starts long before the ship arrives.

What are the most common reasons for MGO port rejection?

Port rejection of marine gas oil is rarely about the sulfur content itself — it is about documentation that cannot be reconciled, samples that do not match the BDN, or supplier data that cannot be verified.

• Missing or incomplete BDN fields: blank density, no flashpoint entry, or a missing signed supplier declaration.
• Sample mismatch: the representative sample cannot be linked to the BDN, or the sample was not drawn under the agreed protocol.
• Change-over record gaps: the ship's records cannot show when the switch to 0.10% sulfur fuel was completed before entering the emission control area.
• Unverifiable supplier: the supplier named on the BDN does not appear on the port state's register of local fuel oil suppliers, which Annex VI requires Parties to maintain.

Every one of these is preventable at the contracting stage. If the price was the only thing negotiated, the documentation was left to chance — and chance is exactly what port state control is paid to eliminate.

What dispute-avoidance protocol should a direct-origin supplier use?

A direct-origin supplier prevents disputes by standardizing the chain: a spec-locked offer, a witnessed sampling protocol, a sealed BDN-matched sample, and a nominated referee laboratory named in the contract.

1. Lock the spec at the offer: quote against the actual cargo with the ISO 8217 grade and edition, plus the density, sulfur, and flashpoint values that will appear on the BDN.
2. Witness the sampling: independent inspectors draw the sample at the terminal or manifold, seal it, and log the seal number alongside the BDN.
3. Match documents to the sample: the BDN, the inspection certificate, and the sample seal all carry the same reference — no fields left open for interpretation.
4. Nominate the referee early: agree the laboratory, the test methods, and the ISO 4259 precision rule before any dispute exists, so a claim becomes a technical exercise, not a standoff.

That protocol is why direct-origin programs resolve quality questions in days rather than months: there is a single document trail from the terminal to the vessel.

How do you verify a supplier can actually deliver compliant MGO?

Verify three things before you award the cargo: physical supply position, documentation discipline, and a compliance track record you can check.

• Physical position: ask for the terminal, the storage, and the loading window. A supplier without a named terminal is a trader with a phone.
• Documentation discipline: review a sample BDN from their recent deliveries. If every Appendix V field is complete and the samples are sealed and numbered, the process is real.
• Track record: ask where their deliveries have been inspected and whether any port state findings were recorded. A direct-origin supplier can answer without hesitation; a broker chain cannot.

MGO is the simplest marine fuel to get wrong on paper and the easiest to get right with process. Buy the process, and the paperwork takes care of itself. For the broader bunker picture including VLSFO, see our VLSFO procurement and quality guide.

Frequently Asked Questions

What changed in the MARPOL BDN rules in August 2025?

Resolution MEPC.385(81), in force since 1 August 2025, extended Bunker Delivery Note requirements to low-flashpoint fuels and gas fuels and clarified the definition of fuel oil. It did not add new BDN fields for marine gas oil; the flashpoint entry for conventional fuels has applied since 1 May 2024 under MEPC.362(79).

What is a Bunker Delivery Note?

A Bunker Delivery Note (BDN) is the legal record of a fuel delivery to a ship, containing product name, quantity, density, sulfur content, flashpoint, and supplier identity. It must be retained on board for three years and be presented to port state inspectors on request.

Is marine gas oil the same as diesel?

Marine gas oil (MGO) is a distillate marine fuel, close to onshore diesel but specified under ISO 8217 rather than ASTM D975. It is the default compliant fuel for ships without scrubbers in sulfur emission control areas.

What is ISO 8217?

ISO 8217 is the international specification for marine fuels; the current edition is ISO 8217:2024. It sets limits for density, viscosity, sulfur, flash point, and contaminants, while disputed test results are interpreted using the precision procedures of ISO 4259.

What happens if a bunker delivery note is missing at port?

A missing or defective BDN is treated as a MARPOL deficiency, not an administrative gap. The port state can detain the vessel, open an inspection file, and report the deficiency. The vessel and the supplier bear the commercial consequences.

Summary

Three takeaways for your next MGO bunker purchase:

• Check every Appendix V field, including the flashpoint entry, and keep the BDN for three years and the sealed sample for at least 12 months.
• Contract against ISO 8217:2024 with ISO 4259 precision rules: spec-locked offer, witnessed sampling, and a nominated referee laboratory.
• Qualify suppliers on physical position and documentation discipline, not on the offer price alone.

Planning a bunker stem or reviewing a supplier's BDN process? Submit a marine fuel RFQ or read the ULSD specification checklist for the onshore diesel picture.

References

1. International Maritime Organization — Fuel oil availability and quality, MARPOL Annex VI Regulation 18: the regulation behind the Appendix V BDN content, three-year BDN retention, and the 12-month representative sample retention period.
2. IBIA — Definition of fuel oil and provision of BDNs for low-flashpoint fuel or gas fuel: the BDN requirements for low-flashpoint and gas fuels in force from 1 August 2025.
3. Lloyd's Register — Class News 04/25: summary of resolution MEPC.385(81) and its 1 August 2025 entry into force.
4. Lloyd's Register — Class News 06/24: the flashpoint entry on BDNs under MEPC.362(79), applicable from 1 May 2024.
5. Britannia P&I — ISO 8217:2024 updates to marine fuel standards: the changes in the current ISO 8217 edition and its general requirements clauses.
6. CIMAC WG7 — ISO 8217:2024, the interpretation of marine fuel analysis test results: guidance on applying ISO 4259 precision to ISO 8217 limits.