Major Kubashack was commissioned in the United States Marine Corps on May 22, 2015 following completion of Officer Candidates School through Naval Reserve Officer Training Corps and graduation from the University of San Diego with a Bachelors of Arts in Economics. Upon completion of The Basic School, he reported to NAS Pensacola, Florida for flight training and earned his wings as a Naval Aviator on June 15, 2018. 

Upon successful completion of initial training in the MV-22B at Marine Medium Tiltrotor Squadron 204 in New River, North Carolina, Major Kubashack was then assigned to Marine Medium Tiltrotor Squadron (VMM) 166 at Marine Corps Air Station Miramar, California in January of 2019. There he served as the Current Operations Officer and deployed to Al Jaber Airbase, Kuwait in support of Special Purpose Marine Air Ground Task Force - Crisis Response – Central Command and Operation Inherent Resolve from March to September 2020. 

While a member of VMM-166, he was selected to attend Aviation Safety Officer (ASO) school and assumed the role of Squadron ASO until the squadron was retired as part of Force Design 2030. 

In May 2021, Major Kubashack reported to VMM-163, MCAS Miramar, California. Major Kubashack served as the Flight Equipment and Ordnance Officer in Charge and Quality Assurance Officer from 2021 to 2022.  Major Kubashack attended and graduated the Weapons and Tactics Instructor Course before deploying to Djibouti in support of Aviation Combat Element - Crisis Response - Africa from April to September 2022.

Following his return from deployment, Major Kubashack assumed the Pilot Training Officer role and was selected as the U.S. Indo-Pacific Command (INDOPACOM) Summer Exercise Series Action Officer for one of the largest 3rd Marine Aircraft Wing exercises to be held in decades, Marine Air Support Activity (MASA) 23. Major Kubashack served as the Remain Behind Element Operations Officer during MASA 23 from June 2023 until August 2023 when the squadron reconsolidated.

In March of 2024, Major Kubashack assumed the role as the Director of Safety and Standardization within the Department of Safety, Standardization, and NATOPS before assuming his role as the Executive Officer of VMM-163 in April of 2024. 

Major Kubashack has flown more than 1000 hours in tactical aircraft, including over 150 combat flight hours. His personal decorations include the Air Medal (Numeral 2), the Navy and Marine Corps Achievement Medal, the Operation Inherent Resolve Medal (2 bronze stars), the Global War on Terrorism Expeditionary Service Medal, the Global War on Terrorism Service Medal, Sea Service Deployment (1 bronze star), and the National Defense Service Medal.