Martin Hathaway, from the Mid Yorkshire Chamber of Commerce, said industry had received "so little information" from ministers about how to adjust.
The UK is nearing the end of its 11-month transition period after it officially left the European Union at the end of January this year.
It means that after December 31, the EU's trading rules will cease to apply here. But with a trade deal between the government and the EU still yet to be struck, there is uncertainty about whether or not tariffs will be slapped on goods being brought into the country and at what cost.
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Speaking at Wakefield's Covid recovery board on Monday, Mr Hathaway, who called for more answers from the government on the issue back in July, said: "The preparedness of businesses for Brexit in this area is very very low.
"There's been so little information that's come out from government over the last 12 months on what needs to be done.
"We need to start making sure businesses have just done the bare minimum that they can.
"One of the things we know, though we don't know what the terms it will be, is that there will be a customs border of some kind between the UK and the rest of Europe.
"We are working with the Department of International Trade and others to find out what it is that businesses need to do."
Mr Hathaway said the Chamber of Commerce, which covers Halifax as well as Huddersfield, was fielding "more queries" about the issue, but added, "With seven-and-a-half weeks to go, it's a little bit late in the day to start looking at what you have to do for imports and exports."
Local Democracy Reporting Service