You might think you've submitted your revalidation to HHH MAC CGS and that that task is over -- but it could cost you your Medicare billing privileges if you've made one of the common mistakes CGS is seeing. Mistake #1: CGS does not consider your enrollment application received until the application fee is paid. This goes for providers that have applied for hardship exemptions as well, CGS stresses. Mistake #2: When using internet-based PECOS, you need to mail the certification statement within 15 days of the application's submission date in the system, CGS instructs. Mistake #3: If you receive a letter from CGS requesting payment of the enrollment fee, you must fax the payment confirmation so the MAC can begin processing your application, CGS says. Contact information is in the message posted on CGS's website at www.cgsmedicare.com/hhh/pubs/news/2012/0212/WR497.html. CGS had received only 10 percent of required enrollment revalidations as of the week before the Feb. 27 deadline, reported the National Association for Home Care & Hospice.