The defender missed the end of Manchester United’s season and Sunday’s opening win over Croatia but is in contention to play some part at Wembley on Friday evening.
Maguire said earlier this week that he would be available for selection and Gareth Southgate confirmed as much on the eve of the game, revealing that the 28-year-old has a chance of playing from the off.
“Harry will be involved tomorrow,” Southgate said. “The decision we've got to make is whether he's ready to start but we're really pleased with his progress.
“He's trained with the team for four or five days now and had no reaction. Each session that he's involved with he gets more confident and I think he's on a really good path.
“Of course we want everybody available. It causes difficult decisions but at the moment this morning on the training pitch we had 26 players training and that's a great situation for us to be in.”
Maguire was one of three players left out of Southgate’s 23-man matchday squad against Croatia, with Ben Chilwell and Jadon Sancho also left out.
England will progress to the knock-out stages if they beat Scotland in the first meeting between the historic rivals at a major tournament in 25 years.
Scotland have received an injury boost of their own, with Steve Clarke confirming that Kieran Tierney has recovered from a knock and will available for selection.