Amanda (TeksMed Services): Being on Probation does not bar a worker from claim, however the Duty to Maintain employment only applies to workers who have been employed for at least 12 months. Many workers have underlying or pre-existing conditions, the Board can consider accepting this as only an aggravation to a pre-existing condition and/or may also consider granting the Employer Relief of Costs in such cases if an underlying or pre-existing condition is enhancing the injury or prolonging the recovery.