Shipping companies have the opportunity to be taxed in accordance with tonnage tax regulations i.e. pay a fixed amount of tax per tonne deployed. This means pre-tax income does not matter - even if you lose money, you have to pay tax.

"However, if you are suddenly extremely profitable, like with the carriers in 2021, you get a competitive edge versus carriers that cannot avail of tonnage tax," says Sea-Intelligence in its update.

Three large carriers (Maersk, Hapag-Lloyd, and CMA CGM) fall under the tonnage tax rules, and have a tax rate of 0.7-3.7 percent while ZIM and Matson do not and have a higher tax rate of 18-21 percent.

"Looking at the three larger carriers against the average tax rate paid per TEU across these three carriers, we found that Maersk had a tax disadvantage of $10.3/TEU, CMA CGM was mainly neutral, and Hapag-Lloyd had a tax advantage of $10.7/TEU. This translated into a tax disadvantage of $269 million for Maersk, a $10 million disadvantage for CMA CGM, and a $127 million advantage for Hapag-Lloyd."

What is interesting, Sea-Intelligence said, is to see how the two carriers (who do not have a tonnage tax) compared to these larger carriers in terms of a tax relative to competitive advantage/disadvantage. "We found ZIM paid $953 million and Matson paid $229 million in 2021 compared to a situation where their taxation per TEU had been the same as for the big three tonnage-taxed carriers."

Another way of looking at it is shown in figure 1 "where we have calculated how much additional tax in TEU is paid whenever the pre-tax income per TEU increases by $100. The difference is very clear to see. For the big three carriers, every time the pre-tax profit increases by $100/TEU, the taxation increases $0.30-1.80/TEU. For ZIM and Matson, the increase in taxation as the pre-tax profit goes up by $100/TEU is $18 and $26/TEU, respectively."