Hint: Record all beneficiary insurance cards, not just the Medicare one. Don't let Medicare Secondary Payer get you -- and your cash flow -- down. You can avoid common MSP billing errors if you take heed of CMS's latest instructions on the bill type, which the agency issued last week as part of a MLN Matters article. Take a look at the Centers for Medicare & Medicaid Services' latest MSP billing tips to ensure that your claims process correctly the first time you submit them. 1. Ask Patients About All of Their In-surers. Ask a patient for all of his insurance cards. In some cases, a patient will present only his Medicare identification card, failing to give you any ad-ditional cards. This could cause unnecessary denials if you're inappropriately billing Medicare as primary. 2. Bill Primary Payer First, Not Simul-taneously. You can't submit claims to the patient's primary payer and the MSP at the same time. Instead, you must bill the primary payer and then wait for the remittance advice from that insurer before you submit to the MSP. "If a patient is seen for multiple services, each service should be billed to the appropriate primary payer," CMS says in MLN Matters article SE1217. 3. Single out Accident Claims. If your patient has an open MSP liability, no-fault, or workers' compensation record, you should bill those payers first, but do not deny treatment, CMS advises. You'll submit to the accident payer first (for instance, the workers' comp insurer), and then to MSP with the first payer's remittance information. If the accident payer did not pay you for the accident-related services, "Medicare will need this information to process your claim accordingly," the MLN Matters article notes. "If you follow these procedures, you do not need to wait 120 days to submit your claim to Medicare for payment." 4. Claims Include EOB. If you're not yet billing electronically, don't forget to include the primary payer's explanation of benefits (EOB) when you submit your paper claim to the MSP, notes a CGS Medicare directive from last summer. Note: The MLN Matters article is at www.cms.gov/Outreach-and-Education/Medicare-Learning-Network-MLN/MLNMattersArticles/downloads/SE1217.pdf.