The US global effective tariff rate has risen to levels last seen in the 1930s, with stark impacts for its closest trading partners, Commonwealth Bank analysis has found.

Last Friday (AEST), US President Donald Trump announced fresh tariff rates as the ‘Liberation Day’ tariff pause expired.

Commonwealth Bank economists estimated that the newly announced tariffs have brought the US effective tariff rate up to 19 per cent, aligning with the bank’s “worst case scenario.”

“Based on the tariff announced so far, we estimate the effective US global tariff rate will stand at around 19% from 7 August,” the economists said.

“This is a little lower than the effective tariff rate that would have resulted if the ‘Liberation day’ tariffs announced on 2 April had gone ahead. And about what we had previously judged to be a worst case scenario.”

The US’ closest trading partners are in for an economic slowdown under the new tariff rates, with Canada to be hit the hardest, the economists said.

Given that 17 per cent of Canada’s GDP was exposed to US demand and it received a relatively high tariff rate of 35 per cent, CBA predicted that Canadian GDP would be 3.3 per cent lower over the medium term due to the tariffs.

Australia’s lower exposure to the US market (five per cent of its total exports) and relatively low tariff rate (10 per cent) led to a predicted GDP slowdown of 0.3 per cent, CBA found.

It added that Eurozone GDP would be approximately 0.6 per cent lower, but pharmaceutical tariffs would exacerbate the slowdown.

The economists anticipated that the tariffs would also hit the US economy hard, raising business and consumer prices and thus dampening demand. Soft demand would likely result in a weaker labour market.

The US also flagged that it would crack down on “illegal” transhipment, wherein goods from high-tariffed countries are rerouted through lower-tariff countries to reduce their tariff bills.

The administration warned that goods identified as transhipped would be pinned with punitive tariff rates of up to 40 per cent.

Accounting firm BDO said that the heightened focus on transhipment would boost the importance of supply chain transparency and robust country of origin rules for Australian exporters.

Uncertainty also prevailed regarding sector-specific tariffs, which currently include a 50 per cent tariff on copper products, a 50 per cent tariff on steel and aluminium, and a 25 per cent tariff on automotive exports.

Timber, semiconductors, pharmaceuticals, trucks, processed critical minerals, commercial aircraft, drones and polysilicon could be next on the chopping block if a US Commerce Department investigation uncovers national security risks related to such imports.

“Should the US President determine that these imports pose a national security risk, the outcome could include significant new tariffs or import restrictions, potentially reshaping market access for Australian exporters,” BDO said.

While uncertainty remains regarding sector-specific tariffs and some country-by-country negotiations, CBA economists predicted that the bulk of tariff-related news had already passed.

“With trade frameworks now agreed (or close to agreement) with many of the major economies, and rates set for most smaller economies, we judge that we are through the bulk of the major tariff-related news.”

“There will still be further negotiations, but we expect President Trump will gradually shift his focus back towards domestic-related issues.”