If you have an illness that requires medical treatment at the time you join a health insurance plan, this illness may be treated as a pre-existing condition. Insurance companies differ in the way they handle pre-existing conditions. Some insurers may deny coverage for a pre-existing illness, while others will offer in person or online health coverage after a certain amount of time, called the exclusion period, has passed. Learning about common pre-existing conditions may prepare you for the way an insurance company will approach your application for coverage.
According to the Health Insurance Portability and Accountability Act, or HIPAA, applicants who have had health insurance within the year before they applied for coverage must receive coverage for a pre-existing condition without an exclusion period.  If you have not had health insurance for more than 12 months when you apply, however, you may be required to wait for coverage or pay a higher rate for treatment. If you have not been covered for one year or more and you received treatment, care or diagnosis for a condition within 6 months before joining a plan, you may be subject to an insurer’s requirements for pre-existing conditions.
The type of pre-existing condition that you have may make a difference in how an insurance provider treats this illness and whether you’ll be required to pay a higher premium. Having a history of cancer may affect your insurance costs, even if you haven’t had a recurrence of symptoms or been treated for the disease in a number of years. Because cancer is a disease that may recur or spread to other body systems, and because the costs of treatment can be very high, insurance providers may charge higher premiums. They may also impose a waiting period on coverage if you had treatment within the past 6 months.
Heart disease, asthma, high blood pressure, high cholesterol and Type 2 diabetes are common pre-existing conditions in the United States. As the population ages, conditions like heart attack, stroke, arthritis and osteoporosis may become more common. Chronic injuries, such as carpal tunnel syndrome, may be considered pre-existing conditions if you received treatment for these conditions within 6 months before you applied for coverage. Less serious conditions, like minor allergies, may also be considered pre-existing illnesses, and you may be required to wait for treatment.
Restrictions on Pre-existing Conditions
Federal law imposes limits on the conditions that can be treated as pre-existing illnesses by insurance companies. With some types of health insurance, pregnancy cannot be treated as a pre-existing condition, even if a woman did not have insurance during the year before she applies for coverage. Check with your insurance provider about whether pregnancy is considered a pre-existing condition under your policy.
Infants and children who have recently been adopted are not subject to pre-existing condition exclusions, as long as they have had health insurance within 30 days of being born, adopted or placed for adoption. Applicants who have a genetic predisposition to a particular illness, such as cancer, may not be subject to pre-existing condition requirements, unless they have been diagnosed or received care or treatment for the disease in the past 6 months. 
As you learn about the common pre existing conditions, consider how your medical history might affect your health insurance. If you have a condition like diabetes, cancer, multiple sclerosis, asthma or hay fever, you can protect your health insurance benefits by maintaining consistent coverage. To avoid interruptions in your treatment for a pre-existing condition, consider investing in short term health insurance if you find yourself without coverage for an extended period of time.