The first iteration of the United Nations Economic Commission for Europe (UNECE) Single Window Recommendation was about 20 years ago. The current 2020 version has not moved much further than the first one. 

It states: 

"One approach to addressing this problem is the establishment of a Single Window federating all relevant government administrations whereby all trade-related information and/or documents need only be submitted once at a single-entry point. This can enhance the availability and handling of information, expedite and simplify information flows between trade and government, and can result in greater harmonisation and sharing of the relevant data across governmental systems, bringing meaningful gains to all parties involved in cross-border trade. The use of such a facility can result in the improved efficiency and effectiveness of official controls and can reduce costs for both Governments and traders due to better use of resources. 

The Single Window is therefore a practical application of trade facilitation concepts meant to reduce non-tariff trade barriers and can deliver immediate benefits to all members of the trading community" 

In fact, I will be leading on the UN/CEFACT Recommendation 18 'International Trade Procedures' review and, during a meeting yesterday, also gave my views on where Single Window should be going. 

I should add that my views on what a modern SW platform should do are much more expansive than the recommendations. So, here are my thoughts: 

1. The Test of an Effective Single Window 
   If an average SME importer or exporter whose transaction is non-contentious (no licences required, no SPS, etc.) benefits from SW's introduction, then the system is successful. It is all about reducing the time and cost of conducting an import or export transaction (to address Lorenzo's point, it should be for export as much as import, although it will always accrue more benefit for importers). Most SWs tend to benefit the relatively small proportion of more complex transactions (like SPS or dual-use goods), and whilst this is clearly very good, it does mean that the majority of traders do not see any great benefit. 
    
2. The Scope of a Single Window 
   I believe that, globally, we should now look at SW Version 2 with a much more inclusive remit, providing a real 'single point of entry' for traders and, in other words, not just connecting government / regulatory agencies (such as HMRC, SPIRE, DEFRA, MOD etc) but also private sector stakeholders such as carriers, freight forwarders, chambers of commerce, port authorities (please see next point) and the traders themselves. The current, prevalent model of SW, only addressing regulatory agencies/procedures, covers 25% of international supply chain processes. The other three elements (commercial, transport, financial) are not addressed. This necessarily constrains the trade facilitation benefits to importers and exporters. 
   
3. Port Authorities 
   A small but important point. Under International Maritime Organization (IMO) rules, every port must now establish a Port Community System, so in countries that also have a Single Window, the danger is that they have a Double Window rather than a Single Window. 
    
4. Single Window and the WTO Trade Facilitation Agreement (TFA) 
   Article 1 of the TFA covers establishing Trade Information Portals. The TFA also 'encourages' countries to establish a Single Window. My view is to combine the two to provide a really effective trade facilitation tool, a true 'one-stop shop' 
   
5. Should the UK Single Window Include the Tariff Tool /Declaration Submission etc? 
   Actually, I think it should. Traders should be able to access a single platform for all their import and export process needs. This should include tools, rules, documents, and information on global market access. My vision of a UK SW would be to combine CDS, SPIRE, and other cross-border trade processes with a trade information portal, such as the EU Access2Markets. It is a big task, and it would be a phased approach over a number of years, but this is what the endgame for a 21st-century platform should look like. I am sensitising (I hope!) UNCEFACT to amend/update Recommendation 33 on Single Window to reflect this concept. 
   
6. User Test Comment 
   One of my CIofEx students who has tested the SW mentioned that to carry out the functions she was performing; she actually needed two windows open. She said that, in her view, traders will be really disappointed by what the UK SW will deliver for them. She said it will under-deliver on the expectations of most importers and exporters. 
   
7. Cost v Benefit  
   Of course, this will be key for HMG. They need to understand that, under the current SW design/intention, a considerable proportion of the importer/exporter/forwarder community will see little or no benefit from the SW.   

Essentially, SW should no longer just be an interface between traders and government agencies. New and evolving platforms should be designed to be expandable to encompass all export/import functions, including shipping instructions, CofO applications, insurance instructions, port devices, manifests, etc. 

I think any country currently establishing their first SW has a real opportunity to design a trade facilitation tool that can benefit every importer and exporter - but the level of ambition really needs to increase if significant benefit is to be achieved. SW is a twenty-year-old concept, and it seems strange that current iterations are remarkably similar to the first ones.