diff --git a/x-pack/plugins/ml/public/application/jobs/new_job/common/job_creator/rare_job_creator.ts b/x-pack/plugins/ml/public/application/jobs/new_job/common/job_creator/rare_job_creator.ts
index dd311ec157422..a5d052f350ea3 100644
--- a/x-pack/plugins/ml/public/application/jobs/new_job/common/job_creator/rare_job_creator.ts
+++ b/x-pack/plugins/ml/public/application/jobs/new_job/common/job_creator/rare_job_creator.ts
@@ -7,8 +7,8 @@
 
 import { SavedSearchSavedObject } from '../../../../../../common/types/kibana';
 import { JobCreator } from './job_creator';
-import { Field, SplitField } from '../../../../../../common/types/fields';
-import { Job, Datafeed } from '../../../../../../common/types/anomaly_detection_jobs';
+import { Field, SplitField, Aggregation } from '../../../../../../common/types/fields';
+import { Job, Datafeed, Detector } from '../../../../../../common/types/anomaly_detection_jobs';
 import { JOB_TYPE, CREATED_BY_LABEL } from '../../../../../../common/constants/new_job';
 import { getRichDetectors } from './util/general';
 import { IndexPattern } from '../../../../../../../../../src/plugins/data/public';
@@ -23,6 +23,8 @@ export class RareJobCreator extends JobCreator {
   protected _type: JOB_TYPE = JOB_TYPE.RARE;
   private _rareInPopulation: boolean = false;
   private _frequentlyRare: boolean = false;
+  private _rareAgg: Aggregation;
+  private _freqRareAgg: Aggregation;
 
   constructor(
     indexPattern: IndexPattern,
@@ -32,6 +34,16 @@ export class RareJobCreator extends JobCreator {
     super(indexPattern, savedSearch, query);
     this.createdBy = CREATED_BY_LABEL.RARE;
     this._wizardInitialized$.next(true);
+    this._rareAgg = {} as Aggregation;
+    this._freqRareAgg = {} as Aggregation;
+  }
+
+  public setDefaultDetectorProperties(rare: Aggregation | null, freqRare: Aggregation | null) {
+    if (rare === null || freqRare === null) {
+      return;
+    }
+    this._rareAgg = rare;
+    this._freqRareAgg = freqRare;
   }
 
   public setRareField(field: Field | null) {
@@ -40,12 +52,21 @@ export class RareJobCreator extends JobCreator {
     if (field === null) {
       this.removePopulationField();
       this.removeSplitField();
+      this._removeDetector(0);
       this._detectors.length = 0;
+      this._fields.length = 0;
       return;
     }
 
+    const agg = this._frequentlyRare ? this._freqRareAgg : this._rareAgg;
+
+    const dtr: Detector = {
+      function: agg.id,
+    };
     if (this._detectors.length === 0) {
-      this._detectors.push({ function: ML_JOB_AGGREGATION.RARE });
+      this._addDetector(dtr, agg, field);
+    } else {
+      this._editDetector(dtr, agg, field, 0);
     }
 
     this._detectors[0].by_field_name = field.id;
@@ -73,7 +94,9 @@ export class RareJobCreator extends JobCreator {
   public set frequentlyRare(bool: boolean) {
     this._frequentlyRare = bool;
     if (this._detectors.length) {
-      this._detectors[0].function = bool ? ML_JOB_AGGREGATION.FREQ_RARE : ML_JOB_AGGREGATION.RARE;
+      const agg = bool ? this._freqRareAgg : this._rareAgg;
+      this._detectors[0].function = agg.id;
+      this._aggs[0] = agg;
     }
   }
 
diff --git a/x-pack/plugins/ml/public/application/jobs/new_job/common/job_creator/type_guards.ts b/x-pack/plugins/ml/public/application/jobs/new_job/common/job_creator/type_guards.ts
index bf9e0e086ffa3..902d67b82a9e3 100644
--- a/x-pack/plugins/ml/public/application/jobs/new_job/common/job_creator/type_guards.ts
+++ b/x-pack/plugins/ml/public/application/jobs/new_job/common/job_creator/type_guards.ts
@@ -49,8 +49,6 @@ export function isCategorizationJobCreator(
   return jobCreator.type === JOB_TYPE.CATEGORIZATION;
 }
 
-export function isRareJobCreator(
-  jobCreator: JobCreatorType
-): jobCreator is CategorizationJobCreator {
+export function isRareJobCreator(jobCreator: JobCreatorType): jobCreator is RareJobCreator {
   return jobCreator.type === JOB_TYPE.RARE;
 }
diff --git a/x-pack/plugins/ml/public/application/jobs/new_job/pages/components/pick_fields_step/components/bucket_span_estimator/estimate_bucket_span.ts b/x-pack/plugins/ml/public/application/jobs/new_job/pages/components/pick_fields_step/components/bucket_span_estimator/estimate_bucket_span.ts
index 7455ffcd1c5a4..67673901494c7 100644
--- a/x-pack/plugins/ml/public/application/jobs/new_job/pages/components/pick_fields_step/components/bucket_span_estimator/estimate_bucket_span.ts
+++ b/x-pack/plugins/ml/public/application/jobs/new_job/pages/components/pick_fields_step/components/bucket_span_estimator/estimate_bucket_span.ts
@@ -14,6 +14,7 @@ import {
   isMultiMetricJobCreator,
   isPopulationJobCreator,
   isAdvancedJobCreator,
+  isRareJobCreator,
 } from '../../../../../common/job_creator';
 import { ml } from '../../../../../../../services/ml_api_service';
 import { useMlContext } from '../../../../../../../contexts/ml';
@@ -49,6 +50,13 @@ export function useEstimateBucketSpan() {
     data.splitField = jobCreator.splitField.id;
   } else if (isPopulationJobCreator(jobCreator) && jobCreator.populationField !== null) {
     data.splitField = jobCreator.populationField.id;
+  } else if (isRareJobCreator(jobCreator)) {
+    data.fields = [null];
+    if (jobCreator.populationField) {
+      data.splitField = jobCreator.populationField.id;
+    } else {
+      data.splitField = jobCreator.rareField?.id;
+    }
   } else if (isAdvancedJobCreator(jobCreator)) {
     jobCreator.richDetectors.some((d) => {
       if (d.partitionField !== null) {
diff --git a/x-pack/plugins/ml/public/application/jobs/new_job/pages/components/pick_fields_step/components/rare_field/description.tsx b/x-pack/plugins/ml/public/application/jobs/new_job/pages/components/pick_fields_step/components/rare_field/description.tsx
index a78a4b8e0cd30..4c3b547d580d7 100644
--- a/x-pack/plugins/ml/public/application/jobs/new_job/pages/components/pick_fields_step/components/rare_field/description.tsx
+++ b/x-pack/plugins/ml/public/application/jobs/new_job/pages/components/pick_fields_step/components/rare_field/description.tsx
@@ -19,7 +19,7 @@ export const Description: FC = memo(({ children }) => {
       title={<h3>{title}</h3>}
       description={
         <FormattedMessage
-          id="xpack.ml.newJob.wizard.pickFieldsStep.splitField.description"
+          id="xpack.ml.newJob.wizard.pickFieldsStep.rareField.description"
           defaultMessage="Select a field in which to detect rare values."
         />
       }
diff --git a/x-pack/plugins/ml/public/application/jobs/new_job/pages/new_job/page.tsx b/x-pack/plugins/ml/public/application/jobs/new_job/pages/new_job/page.tsx
index 442bdba717f28..c5d9acce1ee93 100644
--- a/x-pack/plugins/ml/public/application/jobs/new_job/pages/new_job/page.tsx
+++ b/x-pack/plugins/ml/public/application/jobs/new_job/pages/new_job/page.tsx
@@ -24,6 +24,7 @@ import {
   jobCreatorFactory,
   isAdvancedJobCreator,
   isCategorizationJobCreator,
+  isRareJobCreator,
 } from '../../common/job_creator';
 import {
   JOB_TYPE,
@@ -171,6 +172,10 @@ export const Page: FC<PageProps> = ({ existingJobsAndGroups, jobType }) => {
 
       const { anomaly_detectors: anomalyDetectors } = getNewJobDefaults();
       jobCreator.categorizationAnalyzer = anomalyDetectors.categorization_analyzer!;
+    } else if (isRareJobCreator(jobCreator)) {
+      const rare = newJobCapsService.getAggById('rare');
+      const freqRare = newJobCapsService.getAggById('freq_rare');
+      jobCreator.setDefaultDetectorProperties(rare, freqRare);
     }
   }