This is a policy on what level of import tax it will charge on every imaginable type of product.
Previously, all EU Members had the same tariffs, so it didn't need one.
This is the UK's WTO Goods Schedule.
explaintrade.com/articles/2018/…
In other words, it agreed that its tariffs after Brexit would only ever be set as high as the tariffs of the European Union can legally go.
This would be the taxes importers would ACTUALLY pay at the border, where as the WTO schedule was how much the UK COULD legally make them pay.
gov.uk/government/new…
Politically it allowed pro-Brexit campaigners to trumpet an immediate Brexit dividend, claiming goods on supermarket shelves would become radically cheaper.
Hugely exaggerated but probably convincing.
explaintrade.com/articles/2019/…
Economists also generally hold liberalization to be a broadly good thing to for an economy.
This quickly proved a problem in the Canada FTA rollover.
buzzfeed.com/alexspence/can…
The UK argued its regime was 'temporary' but Canada wasn't convinced.
In trade negotiations, offering to reduce tariffs is a pretty big bargaining chip.
But unilaterally lowering tariffs was one of the benefits it touted from leaving the Customs Union. See idiot headlines:
express.co.uk/news/politics/…
This will strengthen the UK's hand in FTA talks, but undermine an (ok, somewhat spurious) argument for hard Brexit.
Maybe.
explaintrade.com/articles/2018/…