As it stands right now, the Celtics have 11 guaranteed contracts:
Marcus Smart is still in restricted free agency limbo and Daniel Theis and Semi Ojeleye’s contracts don’t guarantee until July 10th and 15th. If everybody returns, that’s 14 of 15 roster spots filled. Abdel Nader, who’s recovering from wrist surgery and won’t be playing in Summer League, is non-guaranteed until August 1st.
In terms of cap space and exceptions--depending on whether or not Marcus Smart signs and for how much--could still have the non-tax payer mid-level exception (MLE).