"Zero-balancers" were a distinct group in the second colonial wave that settled on the planet Manticore after the Great Plague in the second half of the 15th Century PD. Those colonists who completely exhausted their credit to buy the passage to Manticore were known as "zero-balance" immigrants and did not become full citizens until they had become well-enough established to pay taxes for five consecutive Manticoran years (8.7 T-years).