# Coverage Periods

<table><thead><tr><th width="314">Ideon </th><th width="121.33333333333331">Provide?</th><th>Usage and Mapping</th></tr></thead><tbody><tr><td>external_identifier*</td><td><mark style="background-color:red;"><strong>Required</strong></mark></td><td>This is an identifier that your system can use or generate to identify the coverage period. This is in addition to our <code>id</code> for a coverage period.</td></tr><tr><td>coverage_start_date*</td><td><mark style="background-color:red;"><strong>Required</strong></mark></td><td><strong>Required</strong>. This is the most recent policy start date for the employer at the given carrier. <br><br>Note:<br>- Map a recent (rather than original) effective date for the carrier policy.<br>- Coverage periods can have different start dates per carrier for one employer. </td></tr><tr><td>coverage_end_date</td><td><mark style="background-color:green;">Preferred</mark></td><td>This is the most recent policy effective end date for the employer at the given carrier. <br><br>Note:<br>- Map the most accurate date at the time of creation. If a policy is extended, we can adjust our system to display a more accurate end date (this date only informs reach-out actions on our end)</td></tr><tr><td>open_enrollment_end_date</td><td><mark style="background-color:green;">Preferred</mark></td><td>Use these fields to note operational dates around open enrollment. This information is used by our team to inform priorities and upcoming renewals.</td></tr><tr><td>open_enrollment_start_date</td><td><mark style="background-color:green;">Preferred</mark></td><td>Use these fields to note operational dates around open enrollment. This information is used by our team to inform priorities and upcoming renewals.</td></tr><tr><td>additional_information</td><td><mark style="background-color:blue;">Optional</mark></td><td>This is a free-text field that allow special information like:<br><br>- expected client contact<br>- additional mapping information<br>- boolean values to indicate whether a group is part of a PEO, multi-group file.</td></tr><tr><td>carrier_name*</td><td><mark style="background-color:red;"><strong>Required</strong></mark></td><td><strong>Required</strong>. This is the carrier name from Ideon's enum with which the employer has coverage.</td></tr><tr><td>carrier_group_number</td><td><mark style="background-color:green;">Preferred</mark>, <mark style="background-color:red;"><strong>Required by several Carriers</strong></mark></td><td><p>This field holds the "group" or policy number under which the employer is known by the carrier. </p><p></p><p><strong>Several carriers have specific formats and require this number to be provided -</strong>  </p><ul><li><strong>if the number is unknown or a filler value is given, Ideon Operations can override this value for implementation.</strong> </li></ul></td></tr><tr><td>enrollment_type</td><td><mark style="background-color:yellow;">Hardcode</mark></td><td>Default this to <code>member_management</code> </td></tr></tbody></table>
