I'm not sure what a tentative offer is. Was this just a call from the hiring manager - person who interviewed you - telling you that you're going to get an official offer from HR? Or was this actually from HR?
From HR
Congratulations on this tentative offer of employment with U.S. Army Medical Command in Fort Leonard Wood, Missouri as a Physical Therapist, GS-0633-12.
This position is a permanent position.
This offer is contingent upon your ability to successfully complete all pre-employment conditions of employment as stated in the Vacancy Announcement, to include a background investigation. You are required by law and regulation to have a background investigation conducted to determine your suitability for Federal employment and for national security purposes, if required by the position. This must be initiated prior to receiving a firm offer of employment.
This position requires the following Conditions of Employment. If you fail to complete or refuse to acknowledge these requirements, the tentative job offer will be withdrawn. If you are unable to obtain/maintain these requirements, you may be separated from the position and Federal employment. By accepting this tentative job offer, you are acknowledging and agreeing to these Conditions of Employment.
Annual Seasonal Influenza Vaccination
Basic Life Support (BLS)
Immunization Screening/ Hepatitis B
Physical
Childcare Background Check (CNACI)
Drug Testing (TDP)
Credentialing
If you have previously worked for the Federal government and received a Voluntary Separation Incentive Payment (VSIP) in the last five years, you must notify your HR contact of this payment.
Your actual entrance-on-duty date will be established after all pre-employment requirements have been completed and met. Your full suitability/security clearance investigation, as applicable, may be completed after your entrance-on-duty date. Note, you will be submitting all suitability/security clearance forms through a separate Personnel Security Information Portal (PSIP) system.