You may be able to slow your denial volume by simply checking your claim status. TrailBlazer Health Enterprises, the Part B carrier for Delaware, Maryland, Washington, D.C., Virginia, Texas and the Indian Health Service, has released its top-10 billing errors for its most recent quarter -- and results for every state show that duplicate billing is the number-one error across the board. TrailBlazer denied more than a million claims for this reason alone in the fourth quarter. What to do: The carrier suggests that practices should check their claim status before resubmitting claims. Other common errors submitted to TrailBlazer included beneficiary ineligibility, medical-necessity issues, bundled services, claim submitted to the wrong payer, noncovered services, invalid procedure code/modifier combination, missing/invalid group number, provider ineligibility, CLIA issues, and failure to first submit the claim to the beneficiary's primary insurer.