One earlier trip, planning the next
Your client spent 1 March to 30 April 2027 in the Schengen area: 61 days, counting both the entry and the exit day. They want to enter again on 1 July 2027. The 180 days counted back from 1 July start on 3 January 2027, so the whole spring trip is still inside the window: 61 days used, 29 left. They can stay from 1 to 29 July 2027.