Today will bring the first stage in new, wide-ranging Brexit border controls on the import of plants, animals and food to the UK from the European Union.

The changes, the most significant for importers since the UK left the single market three years ago, are poised to have huge ramifications for businesses that rely on imports from the continent.

So what exactly are the changes, and will they push up the prices we pay for food and plants?

What are the new border controls?

At midnight on Tuesday, the government triggered the first stage of a rolling programme of tighter controls on goods entering the UK from the EU. The new system, christened the Border Target Operating Model (BTOM), classifies all plant and animal products coming from the EU and puts them into three risk groups: high, medium and low.

Medium- and high-risk plant and meat products will now require health certificates before they can enter the UK.

High-risk products include plants for planting, some seeds, tubers and live animals.

The medium-risk category covers cut flowers and other parts of plants such as tomato plant cuttings, as well as meat, non-pasteurised milk, eggs and some fish.

From today, anyone exporting meat and dairy products to the UK will need to find a vet in the country of origin to fill out a seven-page form giving assurances that the product is disease-free. For plant products the same assurances will be needed but from a plant health inspector.

Low-risk products, which include some fruit and vegetables such as cucumber and asparagus, processed meats, and cheese made from pasteurised milk, will be exempt from extensive documentation.

What are the next stages?

The most significant change will come on 30 April, when the government begins physical checks at the border on medium-risk and high-risk goods coming into the country.

These checks will take place at specially designated border control posts. Many of these control posts are extensions of existing facilities, which check plant and animal goods coming in from non-EU countries. However, some have been established specifically for these changes. This includes a new £147m facility at Sevington, near Dover, which will process all the products coming through the UK’s busiest port.

The final major change will come in October, with the government requiring safety and security declarations for medium- and high-risk imports, while also introducing a single trade window, which the government says will reduce the number of forms needed for importers.

As of yet, goods coming from the island of Ireland will not require physical checks but the government has said these will be introduced at some point after 31 October this year.

Will the new border controls push up prices?

The government has acknowledged that the extra checks are likely to add to costs for businesses and the consumer.

It has calculated a cost of about £330m a year, and reckons this would push up retail food prices by 0.2% over three years.

However, this may be an underestimate.

This is because the government intends in October to add many more fruit and vegetable products, such as strawberries, apples, sweet potatoes and carrots, to the medium-risk category, meaning additional checks and certification. The Fresh Produce Consortium estimates this will add a further £200m a year to the cost of importing fruit and vegetables from the EU.

There are also concerns that the changes could result in less consumer choice. The Guild of Fine Food, which represents independent food and drink retailers, said smaller suppliers of certain products across the continent were likely to stop exporting to the UK because of the extra red tape.

Why are these changes being made?

First, there is a legal requirement. World Trade Organization rules state that trade borders for the EU must match those of the rest of the world, so as not to give the bloc a trading advantage.

The controls, which have been delayed five times over fears that they could cause disruption and further fuel price inflation, also now mirror those that UK exporters have faced since January 2021.

Meat and dairy farmers, who faced red tape when exporting to the EU while competitors from Europe had unfettered access to UK markets, have welcomed the changes.

The other major reason for imposing controls on incoming goods is biosecurity. The new checks will be important for ensuring that plant and animal diseases, such as xylella, a fast-spreading bacterial disease for plants found in mainland Europe, or African swine fever, which affects pigs, are not imported.