Insurance policies are most often one year terms. You can purchase a shorter term but often there is a penalty applied.

Payment Plan
The 50-50 can be a form of payment plan with 50% of the total premium paid at the start of the policy term with the balance of 50% paid at a later date. The time period is usually 60 - 90 days after the initial payment. The shorter the policy term, the closer the payments would be.

Insurance claim
50-50 can also refer to an automobile claim where the fault is unable to be determined between two parties or equally shared. Both drivers will be show a fault loss. If your policy has an endorsement granting claim forgiveness then you may not see an increase in your premium.

You should discuss concerns in these areas with your agent or broker.