For procurement teams buying ocean freight, the most important number in a shipping contract may no longer be the headline rate. Fuel increasingly sits outside it. Carriers are using bunker adjustment factors, fossil-fuel fees, emissions surcharges and emergency fuel charges to pass changes in marine fuel costs and regulatory expenses through to customers, and the result is that a shipper can secure a long-term freight agreement and still retain substantial exposure to the cost of moving the vessel. That distinction matters because marine fuel risk is no longer driven by crude prices alone: fuel specifications, regional emissions requirements, carbon pricing and geopolitical disruptions can all change what carriers pay to operate a route, and shipping contracts are often structured so that those costs do not remain entirely with the carrier.

A Fixed Freight Rate Does Not Necessarily Fix Fuel Cost

Bunker adjustment mechanisms have existed for years, but the mechanics deserve more attention from procurement teams. Maersk, for example, calculates its bunker adjustment through a Fossil Fuel Fee tied to Platts' fuel price index for 0.5% very-low-sulfur fuel oil and 0.1% low-sulfur marine gas oil, resetting quarterly so bunker charges move with the underlying fuel market rather than leaving the carrier exposed to the gap between the price assumed when a contract was signed and the price actually paid later. For the reference period behind its April 2026 tariff update, Maersk's published averages were $438.20 per metric ton for VLSFO and $675.15 for LSMGO, figures the carrier revises with each quarterly review. Those mechanisms effectively separate two risks: the carrier commits capacity and service, while the shipper retains at least part of the risk that the fuel required to provide that service becomes more expensive. That can make a supposedly fixed annual freight contract behave more like a partially indexed energy contract, not unlike how broader shipping-decarbonization rules are already pushing operating costs into territory that looks more like a compliance fuel budget than a transport line item.

Emergency Charges Add Another Layer

Standard bunker formulas are not always the end of the exposure. In March, Maersk introduced a global Emergency Bunker Surcharge in response to the security situation around the Strait of Hormuz, a corridor the carrier said handles roughly 20% of global fuel trade. Maersk described the resulting disruption as more than a price problem: refineries in the region were operating at reduced capacity, fuel had become unevenly distributed, and the carrier found itself needing to redistribute supplies and secure alternative sources just to bunker its vessels where they actually needed it. The surcharge, the carrier said, was designed to cover fuel availability, cost and mix effects falling outside its standard Fossil Fuel Fee. That distinction matters for procurement, because it shows a shipper can inherit more than ordinary commodity-price risk from a single geopolitical event: price, availability, fuel specification, physical repositioning and geopolitical exposure can all move through the same surcharge line at once.

For long-haul headhaul shipments, the charge reached $400 for a 40-foot dry container and $600 for a 40-foot refrigerated container, with backhaul and intra-trade movements charged at roughly half those levels, and Maersk said the surcharge would be reviewed every 14 days and adjusted upward or downward as conditions changed. The scale becomes clearer with a simple illustration: for a shipper moving 5,000 long-haul 40-foot dry containers under an affected trade lane, a $400 emergency surcharge represents $2 million in additional transportation expense, and the reefer equivalent at $600 per container would add $3 million, before accounting for whatever Fossil Fuel Fee is already built into the base contract. No two shippers would necessarily see exactly those figures, but the arithmetic illustrates how quickly a charge marketed in per-container dollars becomes a material line item across a real volume commitment. That is the contractual issue procurement teams need to recognize: a fuel-adjustment clause may not necessarily establish the maximum fuel exposure if the agreement also permits emergency or contingency surcharges when market conditions move outside the assumptions built into the normal formula.

Regulation Is Expanding the Pass-Through Model

Fuel risk is also becoming regulatory risk. Shipping within the European regulatory system already provides a clear example: Maersk's emissions surcharge covers costs associated with both the EU Emissions Trading System and FuelEU Maritime, recalculating the charge using market prices for European Union Allowances and applying the mechanism to qualifying bookings involving EU or European Economic Area ports. Hapag-Lloyd similarly adjusts its EU ETS surcharge using allowance prices and carrier-specific emissions and vessel-load data, and research into how carriers calculate those emissions has found significant inconsistency in the underlying methodology, which matters directly to shippers now paying a surcharge tied to those same figures. Those charges demonstrate how environmental compliance costs can move from a carrier's operating expense into a customer's freight invoice, and the regulatory map is still changing.

The global IMO sulfur limit remains 0.50%, while designated emission control areas require fuel with sulfur content no higher than 0.10%. The Canadian Arctic and Norwegian Sea officially became ECAs on March 1, 2026. The IMO added another in April, adopting a North-East Atlantic ECA at its 84th environmental committee session covering waters extending from Greenland and Iceland through the United Kingdom, Ireland, France, Spain and Portugal, one of the largest ECAs in the world once it takes effect. The underlying MARPOL amendment enters into force September 1, 2027, with the new sulfur limit taking effect one year later, in September 2028. Meanwhile, the IMO's proposed global Net-Zero Framework, which would introduce a marine-fuel standard and GHG pricing mechanism for large oceangoing ships, was adjourned without adoption in October 2025 after member states voted to delay the vote by a year; the session is now scheduled to reconvene in late 2026, with any framework adopted there unlikely to take legal effect before 2028. For procurement teams, uncertainty does not necessarily eliminate the cost risk. It may make contractual allocation more important, particularly as global maritime emissions keep climbing even as individual efficiency measures improve, keeping pressure on regulators to act regardless of how the Net-Zero Framework timeline ultimately resolves.

Procurement Needs to Read the Formula, Not Just the Rate

Ocean freight negotiations have traditionally centered on base rates, minimum volume commitments, capacity guarantees and service levels. Fuel clauses deserve the same scrutiny before a contract is signed, organized around five questions.

What is actually indexed:

  • Fuel price alone, a carbon price, a specific fuel grade, or some combination?
  • How often does the calculation reset, monthly, quarterly or on some other interval?
  • Does the mechanism move both ways, so that a buyer automatically receives the benefit when fuel prices fall rather than only absorbing increases?
  • What sits outside the formula entirely, whether that is an emergency bunker charge, an emissions surcharge, a war-risk premium or another contingency fee?
  • Can the carrier introduce new surcharges during the contract term at all?

That last question may matter more than the other four combined. The real procurement risk is not simply how a bunker adjustment is calculated. It is what the contract allows the carrier to charge that isn't captured by that calculation in the first place, since a well-understood formula still leaves a buyer exposed if the agreement gives the carrier room to add charges outside it. The issue is not whether carriers should be able to recover legitimate changes in fuel and compliance costs. Fuel represents a major operating expense, and forcing carriers to absorb unlimited volatility would simply push the risk back into higher base pricing. The question is whether procurement teams understand how much of that volatility they have agreed to own. For many ocean freight contracts, the answer is more than the negotiated rate suggests.