In most cases, the mandatory health insurance takes effect on a specific date, often tied to significant life events or enrollment periods. For example, in the United States, the effective date for mandatory health insurance under the Affordable Care Act (ACA) is typically the first day of the month following a 30-day enrollment period. However, specific effective dates can vary based on individual circumstances, so it's important to consult the relevant insurance provider or regulatory authority for precise information on the effective date of mandatory health insurance. Additionally, some countries may have different regulations and timelines for the implementation of mandatory health insurance, so it's essential to consider the specific laws and guidelines applicable to the given location when determining the effective date of mandatory health insurance.