The Blades take on Forest at Bramall Lane on Saturday, with 3,200 tickets being given to away fans.
They have also been priced at £20, as is the same with home supporters.
However, it was announced on Monday that Forest have allocated United just 2,000 tickets, which are priced at £29.
Tickets go on sale on Tuesday morning at 9am, with those supporters with 60,000+ loyalty points getting first priority, with a downward sliding scale of loyalty points getting their chance between Tuesday and Friday. Tickets will go on general sale on Saturday though it is not expected that there will be any remaining by that stage.
Ticket prices are: £29 for adults; £21 for seniors 65+; £14 for young adults aged 18-23; £11 for juniors 11-17 and £6 for juniors aged 4-11.
One United fan posted on twitter: “What!? So we give them 3000 odd and get 2000 in return?!”
Another posted: “This is ridiculous. We’ve given Forest 3,188 tickets on the top tier / corner at £20 a ticket and having to move our season ticket holders etc, for them to give us just 2,000 tickets at £29 each??”
Another said: “So we go out of our way to give them 3,100 and upset our own season ticket holders yet in return get charged £29 and get 2,000. Shambles.”