The Imperial biographer and historian Suetonius saw the aerarium militare as a response to the uncertainty of retired military men in need who might be inclined to support a coup or foment unrest.
[2] The professionalizing of the army during the Republic created the new problem of veterans, since earlier in Rome's history male citizens served short-term to confront specific threats or carry out seasonal campaigns, and then returned to their normal occupations.
[5] A soldier earned a one-time praemium or discharge benefit[6] upon completing his service (sixteen years for the Praetorian Guard, twenty for regular duty in the army).
[8] When the treasury experienced a shortfall, the emperor might avoid paying pensions by arbitrarily extending the length of military service, in a form of forced retention or "stop-loss policy".
[9] In 6 AD, Augustus capitalized the pension fund with 170 million sesterces of his own money,[10] along with voluntary contributions from client kings and cities.
[11] The amount was insufficient, and after soliciting proposals on revenue enhancement from senators, all of which he rejected, he finally forced through an inheritance tax of 5 percent (vicesima hereditatium).