The tier system of coronavirus restrictions has been described as like a "Mensa quiz" by a tourism boss.
People from very high alert areas are advised not to stay overnight elsewhere, but the rules for lower tiers is less clear.
Visit Cornwall's Malcolm Bell described it as a "subtle change" that could create "awkward situations".
"It is a bit of a Mensa quiz on this one as to who should be doing what," he said.
"In tier two you should only really go on holiday in a single household, but tier one you can go as multiple households so long as it's not more than six."
He advised rearranging or refunding bookings for people who have booked from tier three areas, but raised concerns about the lower tiers of restrictions.
Holidaying rules for England
Tier Three - Very high alert - should not visit or stay overnight in another area
Tier Two - High alert - You can go on holiday outside your local area as long as you don't share accommodation with people you don't live or bubble with, or socialise with them in any indoor setting
Tier One - Medium alert - You can holiday anywhere in England that's also in Tier One, following the rule of six and social distancing guidance in private accommodation and avoiding sharing rooms with other households
Mr Bell also urged businesses to make contact with guests in advance "to avoid awkward situations of somebody arriving only for the cottage or hotel owner to tell them they are outside of government guidelines".
Sue Jewell form South East Cornwall Tourism Association described it as a "grey area" because the advice was not law and nobody is banned from travelling.
"We have to refund if we can't come up with a mutual arrangement, which puts all the onus back on the [property] owners, who have had a pretty tough year."
Andrew Baragwanath, from Ayr Holiday Park in St Ives, said his business is checking postcodes and contacting those in tier three areas to discuss rearranging bookings to a later date.
He said: "We haven't yet decided if we're going to ban people from coming, but it may come to that."
The government has been approached for comment.