So i was active duty military but switched to reserves in july after submitting my w-2 should i check the box for active military duty

[LinaJ2020]

Yes, you should still check that box.  If you are a member or former member of the U.S. Armed Forces including active, reserve or National Guard, check the box. 

Members of the armed services are eligible for various tax benefits that can increase their net take-home pay compared with civilians, such as tax-exempt allowances for housing and food.  Although any base pay earned by a member of the armed services while serving in a combat zone is excluded from federal income tax, it is still subject to Social Security tax and Medicare tax.  To learn more, click here: Military