Title I requires the coverage of and also limits restrictions that a group health plan can place on benefits for preexisting conditions. Group health plans may refuse to provide benefits in relation to preexisting conditions for either 12 months following enrollment in the plan or 18 months in the case of late enrollment. Title I allows individuals to reduce the exclusion period by the amount of time that they have had "creditable coverage" before enrolling in the plan and after any "significant breaks" in coverage. "Creditable coverage" is defined quite broadly and includes nearly all group and individual health plans, Medicare, and Medicaid. A "significant break" in coverage is defined as any 63-day period without any creditable coverage. Along with an exception, allowing employers to tie premiums or co-payments to tobacco use, or body mass index.