Asymmetry analysis for trade in goods statistics between the UK and the USA, 2017 to 2022
Published 1 March 2024
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Background
His Majesty’s Revenue and Customs (HMRC) and the Department for Business and Trade (DBT) worked with the United States Census Bureau (Census) to conduct an asymmetry analysis on published trade in goods statistics between the UK and the USA. This was part of the Asymmetry Working Group (AWG).
The analysis looked at differences in how the UK and the USA record and report goods traded between them from 2017 to 2022.
Besides asymmetry for total trade in goods, the analysis focused on the following commodity groupings:
-
Harmonised System (HS) 87: Vehicles; other than railway or tramway rolling stock, and parts and accessories thereof
-
Harmonised System (HS) 8703: Motor cars and other motor vehicles; principally designed for the transport of persons other than those of heading no. 8702, including station wagons and racing cars
Note: these are referred to as HS 87: Vehicles and HS 8703: Cars.
Under the Harmonised System, goods are classified into commodity codes with six digits. The first two digits (HS-2) refer to the Chapter. There are 99 chapters in total. Thus, ‘HS 87’ means all goods with commodity code beginning ‘87’. This group is also known as Chapter 87. The next two digits (HS-4) identify groupings within that chapter. Harmonized Commodity Description and Coding Systems (HS), UN Statistics provides more information.
Annex D explains the focus on HS 87: Vehicles and HS 8703: Cars.
The trade values used in this report are in United States Dollars and are obtained from the United Nations International Trade Statistics Database, also called Comtrade data. When alternative data sources are shown for comparative purposes, this is made clear.
When available, trade data for imports is submitted to UN Comtrade based on the country of origin. If the country of origin is not available, it is submitted based on the country of dispatch. Annex B and Additional country of origin information provide more information about Comtrade data.
Summary
UK trade in goods imports vs USA exports
The asymmetry analysis found incomplete country of origin information likely to be the cause of negative asymmetry for UK imports from the USA before 2022. In 2022, the findings show the negative asymmetry was eliminated when this data was included in the statistics.
Before 2022, data on UK imports from the European Union (EU) came from the Intrastat survey. This survey only collected data on the country of dispatch.
From January 2022, imports to Great Britain (GB) from the EU are collected from customs declarations. For the first time, GB imports from the EU can declare a country of origin. UK imports from non-EU countries have always been able to declare a country of origin. So, now we can report country of origin information for GB imports from all nations.
Additional country of origin information outlines recent changes to country of origin information for UK imports. Annex E defines country of origin and country of dispatch. Annex B explains how the UK and the USA apply these definitions.
In 2022, there was a clear change from negative to positive asymmetry. This change was observed at all three levels of aggregation studied:
- all chapters
- HS 87: Vehicles
- HS 8703: Cars
The shift was most pronounced for HS 8703: Cars, indicating that this sub-category was disproportionately affected.
The data collection change in 2022 may explain the removal of the negative asymmetry. Although, the switch to positive asymmetry remains unexplained. This report includes only one full year’s worth of data since the data collection changed. Thus, the asymmetry may change direction again. Further years’ data will be needed to confirm this. Moving forward, HMRC and Census will review the asymmetry and investigate potential causes.
More detail about trade asymmetries and their calculation can be found in Annex A.
UK trade in goods exports vs USA imports
This main focus of the asymmetry analysis was goods transported from the USA to the UK, rather than the UK to the USA. This is because the asymmetry for UK imports is much larger. For comparison, asymmetry data for UK exports vs USA imports is included in this section. The commentary is less detailed and there is no need to explore potential explanations. This is because there is no large asymmetry for the UK exports flow.
In 2022, the asymmetry for UK total exports was just -$324 million, compared to $20,574 million for UK total imports.
Yet, there is an unexplained shift to positive asymmetry for HS 87: Vehicles and HS 8703: Cars in 2022. This shift is similar to what was seen in UK imports for that year.
The data element ‘country of last known destination’ for UK exports has not changed. It is collected on both the Intrastat survey and customs declarations. Annex E defines this concept. Annex B explains how it is applied by the UK and the USA.
Even so, as for UK imports, the method of data collection has changed. Prior to 2021, UK exports to the EU were collected via the Intrastat survey. Since 2021, GB exports to the EU are now collected using customs declarations.
Introduction
Trade asymmetries occur when a country’s published trade statistics differ from its partners. Each country collects their own data on international trade in goods. In theory, each country’s exports to another should match the other country’s imports. For example, UK imports from the USA should equal USA exports to the UK. In reality, figures often don’t match exactly. These differences are known as trade asymmetries.
There has been asymmetry between the UK and USA published trade in goods statistics for a long time.
In May 2023, the UK released a report on their trade imbalances with countries around the world. The report is called “Asymmetries in international trade in goods statistics: UK measured against EU and non-EU partner countries, 2019 to 2021” and uses Comtrade data. In 2021, the USA ranked 19th out of all countries in absolute asymmetry for UK trade in goods imports, according to this report. For UK trade in goods exports, the USA ranked 9th.
In 2022, HMRC and Census became aware of a shift into positive asymmetry for total UK imports in 2022. This corresponded with the data collection changes for UK data. The overall asymmetry for all chapters was -$1,740 million in 2021 and $20,574 million in 2022 for UK imports. By contrast, the asymmetry decreased on the UK exports side from $2,942 million in 2021 to -$324 million in 2022.
The goal of this analysis was to examine these asymmetry trends and find possible reasons, with a particular focus on HS 87: Vehicles and HS 8703: Cars, as explained in Annex D. Future studies may explore trends and explanations for other types of goods.
UK imports vs USA exports
Total UK imports vs USA exports
Figure 1: Total UK imports vs USA exports, 2017 to 2022
Figure 1 compares the total value of UK imports from the USA with USA exports to the UK for the years 2017 to 2022. Values represent millions of United States Dollars.
Source: Comtrade data, downloaded May 2023.
Download Figure 1 - Total UK imports vs USA exports, 2017 to 2022 (ODS 9.84 KB)
Table 1: Asymmetry between total UK imports and USA exports, 2017 to 2022
| Year | Asymmetry ($ million) |
|---|---|
| 2017 | 2,585 |
| 2018 | -2,999 |
| 2019 | -2,022 |
| 2020 | -754 |
| 2021 | -1,740 |
| 2022 | 20,574 |
Table 1 displays the asymmetry between total UK imports from the USA and USA exports to the UK for the years 2017 to 2022. Values represent millions of United States Dollars.
Source: Comtrade data, downloaded May 2023.
Download Table 1 - Asymmetry between total UK imports and USA exports, 2017 to 2022 (ODS 9.67 KB)
Table 1 shows that the asymmetry was negative for all years except 2017 and 2022.
In 2022 the magnitude of the asymmetry was unusually high. As outlined in the Summary, there was a data collection change in 2022 that may explain the removal of the negative asymmetry. Additional country of origin information provides more details on this change. However, the switch to large positive asymmetry in 2022 remains unexplained.
The largest absolute asymmetry the UK had in 2021 with any country for UK imports was $7,114 million, with Belgium. The Asymmetries in international trade in goods statistics: UK measured against trade partners 2019 to 2021 report provides this information.
Based on provisional 2022 Comtrade data, the USA has the second highest absolute asymmetry with the UK for imports. China has the highest absolute asymmetry at $28,870 million.
UK imports vs USA exports for HS 87: Vehicles
Figure 2: UK imports vs USA exports for HS 87: Vehicles, 2017 to 2022
Figure 2 compares the value of UK imports of HS 87: Vehicles from the USA with USA exports to the UK for the years 2017 to 2022. Values represent millions of United States Dollars.
Source: Comtrade data, downloaded May 2023.
Download Figure 2 - UK imports vs USA exports for HS 87 Vehicles, 2017 to 2022 (ODS 9.8 KB)
Table 2: Asymmetry between UK imports and USA exports for HS 87: Vehicles, 2017 to 2022
| Year | Asymmetry ($ million) |
|---|---|
| 2017 | -1,907 |
| 2018 | -1,728 |
| 2019 | -1,551 |
| 2020 | -1,439 |
| 2021 | -744 |
| 2022 | 547 |
Table 2 displays the asymmetry between UK imports of HS 87: Vehicles from the USA and USA exports to the UK for the years 2017 to 2022. Values represent millions of United States Dollars.
Source: Comtrade data, downloaded May 2023.
Table 2 shows that the asymmetry was strongly negative for all years except 2022.
Between 2017 and 2021, HS 87: Vehicles had an average annual asymmetry of -$1,478 million, compared to just -$986 million for all chapters. HS 87: Vehicles ranked 4th out of all chapters for average negative asymmetry throughout this period.
Annex D outlines further how HS 87: Vehicles compares with other chapters in terms of asymmetry for UK imports from the USA over this period.
In 2022, the asymmetry for HS 87: Vehicles became positive for the first time in this period. This was mirrored in the overall asymmetry for all chapters, which also became positive as Figure 1 showed. HS 87: Vehicles had an asymmetry of $547 million. This was about 3% of the total asymmetry of $20,574 million across all chapters in 2022.
As outlined in the Summary, there was a data collection change in 2022 that may explain the removal of the negative asymmetry. Additional country of origin information provides more detail on this change. However, as for UK imports for all chapters, the switch to positive asymmetry in 2022 remains unexplained.
The following section outlines the asymmetry trends for HS 8703: Cars, which is a large subgroup of HS 87: Vehicles. The Bremerhaven effect further discusses potential reasons for these trends.
UK imports vs USA exports for HS 8703: Cars
Figure 3: UK imports vs USA exports for HS 8703: Cars, 2017 to 2022
Figure 3 compares the value of UK imports of HS 8703: Cars from the USA with USA exports to the UK for the years 2017 to 2022. Values represent millions of United States Dollars.
Source: Comtrade data, downloaded May 2023.
Download Figure 3 - UK imports vs USA exports for HS 8703 Cars, 2017 to 2022 (ODS 9.74 KB)
Every year, HS 8703: Cars drives the asymmetry trend in HS 87: Vehicles. It mirrors the direction and makes up most of its magnitude, ranging from 63% in 2022 to 102% in 2020.
Table 3: Asymmetry between UK imports and USA exports for HS 8703: Cars, 2017 to 2022
| Year | Asymmetry ($ million) |
|---|---|
| 2017 | -1,869 |
| 2018 | -1,546 |
| 2019 | -1,462 |
| 2020 | -1,463 |
| 2021 | -754 |
| 2022 | 345 |
Table 3 displays the asymmetry between UK imports of HS 8703: Cars from the USA and USA exports to the UK for the years 2017 to 2022. Values represent millions of United States Dollars.
Source: Comtrade data, downloaded May 2023.
Table 3 shows that the asymmetry was strongly negative for all years except 2022, mirroring HS 87: Vehicles.
The asymmetry for HS 8703: Cars was strongly negative from 2017 to 2020, like for HS 87: Vehicles. It roughly halved in 2021 and then became positive in 2022, also like for HS 87: Vehicles.
As outlined in the Summary, there was a data collection change in 2022 that may explain the removal of the negative asymmetry. Additional country of origin information provides more detail on this change. However, as for UK imports for all chapters, the switch to positive asymmetry in 2022 remains unexplained.
The Bremerhaven effect considers potential explanations for the asymmetry trends of HS 8703: Cars in more detail.
Additional country of origin information
UK imports from the EU: additional country of origin information from 2022
From 31 December 2020, the free movement of people and goods and services between the UK and the EU ended. Thus, HMRC revised the way they compiled trade in goods statistics.
Trade in goods statistics for UK imports from the EU were not affected by any change in 2021. The Intrastat survey remained the data source for imports from the EU into GB and Northern Ireland (NI) under the NI Protocol. This also eased the effects of staging customs controls.
But, from 1 January 2022, Intrastat only applied for movements of goods between NI and the EU. Statistics on imports to GB from the EU began to be collected from customs import declarations.
When available, trade data for imports is submitted to UN Comtrade based on the country of origin. If the country of origin is not available, it is submitted based on the country of dispatch.
Customs import declarations include country of origin information. Whereas the Intrastat survey operates on a country of dispatch only basis for intra-EU trade. Therefore, country of origin data was not available for UK imports from the EU prior to the data collection change in 2022.
Thus, starting in 2022, country of origin information for GB imports from the EU became available in UN Comtrade statistics.
The publication Impact of trade in goods data collection changes on UK trade statistics Articles - Office for National Statistics (ons.gov.uk) explains more about how the changes in collecting data affect UK trade statistics.
The effect of this on UK imports from the USA
Before 2022, if USA-origin goods cleared EU customs in another EU country before coming to the UK, the UK would count them as imports from the EU.
Conversely, the USA would consider this as exports to the UK. Census defines the partner country as the ‘country of ultimate destination’. They follow the recommendations of the International Merchandise Trade Statistics (IMTS) guidance. Annex B and Annex D provide more information on this concept and how it is applied by the UK and the USA.
So, before 2022, UK imports from the USA and USA exports to the UK are not completely comparable. This explains the negative asymmetry.
From 2022, UK imports from the USA on a country-of-origin basis should be comparable with USA exports to the UK. Instead, there is positive asymmetry in 2022, which cannot be explained.
The Bremerhaven effect
The ‘Bremerhaven effect’ could explain the large negative asymmetry in UK imports of HS 8703: Cars before 2022
The large gap between USA exports and UK imports for HS 8703: Cars before 2022 could be the result of the ‘Bremerhaven effect’.
Bremerhaven is one of the most important German ports. Often referred to as ‘the largest car park in the EU’, it plays a major role in the importing of cars to Europe. Evidence shows large car manufacturers ship USA-origin cars to the UK via Bremerhaven.
Before 2022 when the UK was part of the European Union, these cars would clear customs in Germany. Then they were free to enter the UK without clearing customs again. The Intrastat survey captures trade within the EU on a country of dispatch only basis. Thus, in the trade statistics submitted to UN Comtrade, the UK counted these imports as coming from Germany, not the USA.
Starting in 2022, these movements can be identified by their country of origin. This information is now collected on customs declarations by HMRC. It is also used to compile the UK trade statistics submitted to UN Comtrade.
On the other hand, the USA trade statistics always identified these movements as USA exports to the UK. This is because the USA collects exports on a ‘country of ultimate destination’ basis.
Before 2022, cars going from the USA to the UK were clearing EU customs at Bremerhaven. They would have been considered as USA exports to the UK. In contrast, they would not have been counted as UK imports from the USA in UK trade statistics. This is referred to as the ‘Bremerhaven effect’.
There is anecdotal evidence that this was a popular route before the UK’s exit from the EU. Therefore, this likely accounts for the large negative asymmetry. Even so, it does not explain the positive asymmetry in 2022.
Figure 4: UK imports on a country of origin and country of dispatch basis vs USA exports for HS 8703: Cars, 2017 to 2022
Figure 4 compares USA exports of HS 8703: Cars with two data sources for UK imports from the USA, from 2017 to 2022. Values represent millions of United States Dollars.
The two data sources used for UK imports of HS 8703: Cars from the USA are:
-
UN Comtrade Trade Data, downloaded May 2023
-
UK trade info overseas trade data table, downloaded May 2023 and converted into dollars using ONS exchange rates.
Annex B and Additional country of origin information provide more information about these data sources.
In 2022, UK imports of HS 8703: Cars from the USA increased more than ten times according to UN Comtrade data. This made the asymmetry positive for the first time. In other words, the UN Comtrade 2022 figure for UK imports exceeds USA exports. This is also shown in Figure 2.
In comparison, the OTS data shows that UK imports of HS 8703: Cars from the USA increased by only 50% in 2022. Despite being a series high, the OTS 2022 figure for UK imports is still lower than USA exports.
The two data sources for UK imports do not show a similar increase in 2022. This supports the idea that the ‘Bremerhaven effect’ caused the negative asymmetry in the UN Comtrade data before 2022. It could not have affected the OTS data because it has always been on a country of dispatch basis.
The positive asymmetry in 2022 and the increase in the OTS figures cannot be explained. HMRC and Census will continue to work together to better understand the reasons.
UK exports vs USA imports
Total UK exports vs USA imports
For comparison, the equivalents of Figures 1 to 3 and Tables 1 to 3 for UK exports to the USA are included below.
Figure 5: Total UK exports vs USA imports, 2017 to 2022
Figure 5 compares the total value of UK exports to the USA with USA imports from the UK for the years 2017 to 2022. Values represent millions of United States Dollars.
Source: Comtrade data, downloaded May 2023.
Download Figure 5 - Total UK exports vs USA imports, 2017 to 2022 (ODS 9.73 KB)
Table 4: Asymmetry between total UK exports and USA imports, 2017 to 2022
| Year | Asymmetry ($ million) |
|---|---|
| 2017 | 4,927 |
| 2018 | 4,236 |
| 2019 | 9,396 |
| 2020 | 4,768 |
| 2021 | 2,942 |
| 2022 | -324 |
Table 4 displays the asymmetry between total UK exports to the USA and USA imports from the UK for the years 2017 to 2022. Values represent millions of United States Dollars.
Source: Comtrade data, downloaded May 2023.
Download Table 4 - Asymmetry between total UK exports and USA imports, 2017 to 2022 (ODS 9.66 KB)
Table 4 shows that the asymmetry was positive for all years except 2022, when it was somewhat negative.
UK exports vs USA imports for HS 87: Vehicles
Figure 6: UK exports vs USA imports for HS 87: Vehicles, 2017 to 2022
Figure 6 compares the value of UK exports of HS 87: Vehicles to the USA with USA imports from the UK for the years 2017 to 2022. Values represent millions of United States Dollars.
Source: Comtrade data, downloaded May 2023.
Download Figure 6 - UK exports vs USA imports for HS 87 Vehicles, 2017 to 2022 (ODS 9.7 KB)
Table 5: Asymmetry between UK exports and USA imports for HS 87: Vehicles, 2017 to 2022
| Year | Asymmetry ($ million) |
|---|---|
| 2017 | -86 |
| 2018 | 7 |
| 2019 | 28 |
| 2020 | -64 |
| 2021 | 72 |
| 2022 | 522 |
Table 5 displays the asymmetry between UK exports of HS 87: Vehicles to the USA and USA imports from the UK for the years 2017 to 2022. Values represent millions of United States Dollars.
Source: Comtrade data, downloaded May 2023.
Table 5 shows that the asymmetry was very small compared to the volume of trade for all years except 2022.
UK exports vs USA imports for HS 8703: Cars
Figure 7: UK exports vs USA imports for HS 8703: Cars, 2017 to 2022
Figure 7 compares the value of UK exports of HS 8703: Cars to the USA with USA imports from the UK for the years 2017 to 2022. Values represent millions of United States Dollars.
Source: Comtrade data, downloaded May 2023.
Download Figure 7 - UK exports vs USA imports for HS 8703 Cars, 2017 to 2022 (ODS 9.75 KB)
Table 6: Asymmetry between UK exports and USA imports for HS 8703: Cars, 2017 to 2022
| Year | Asymmetry ($ million) |
|---|---|
| 2017 | -192 |
| 2018 | -65 |
| 2019 | 98 |
| 2020 | -157 |
| 2021 | -48 |
| 2022 | 443 |
Table 6 displays the asymmetry between UK exports of HS 8703: Cars to the USA and USA imports from the UK for the years 2017 to 2022. Values represent millions of United States Dollars.
Source: Comtrade data, downloaded May 2023.
Table 6 shows that the asymmetry was negative for all years except 2019 and 2022, but it is much weaker than for UK imports.
Annexes
The following set of annexes accompany this report: