diff --git a/package.json b/package.json
index bf844ecc8..7a9c5e3af 100644
--- a/package.json
+++ b/package.json
@@ -53,6 +53,7 @@
 		"react-virtualized-select": "^3.1.3",
 		"reduce-reducers": "^0.1.2",
 		"redux": "^3.7.2",
+		"redux-batched-actions": "^0.4.1",
 		"redux-form": "^7.4.2",
 		"redux-thunk": "^2.3.0",
 		"reselect": "^4.0.0",
diff --git a/source/Provider.js b/source/Provider.js
index 4f3631306..b8973c5e7 100644
--- a/source/Provider.js
+++ b/source/Provider.js
@@ -11,6 +11,7 @@ import { applyMiddleware, compose, createStore } from 'redux'
 import thunk from 'redux-thunk'
 import computeThemeColours from 'Ui/themeColours'
 import { getIframeOption, inIframe } from './utils'
+import { enableBatching } from 'redux-batched-actions'
 
 let initialStore = {
 	themeColours: computeThemeColours(getIframeOption('couleur'))
@@ -50,7 +51,7 @@ export default class Layout extends PureComponent {
 			)
 		)
 		this.store = createStore(
-			reducers,
+			enableBatching(reducers),
 			{ ...initialStore, ...this.props.initialStore },
 			storeEnhancer
 		)
diff --git a/source/components/PeriodSwitch.js b/source/components/PeriodSwitch.js
index cd70f0ba2..b69903d34 100644
--- a/source/components/PeriodSwitch.js
+++ b/source/components/PeriodSwitch.js
@@ -2,9 +2,16 @@ import React from 'react'
 import { Trans, translate } from 'react-i18next'
 import { Field } from 'redux-form'
 import './PeriodSwitch.css'
-import { reduxForm } from 'redux-form'
-import { compose } from 'ramda'
+import { reduxForm, change } from 'redux-form'
+import { compose, map, filter, toPairs } from 'ramda'
 import emoji from 'react-easy-emoji'
+import { batchActions } from 'redux-batched-actions'
+import { connect } from 'react-redux'
+import {
+	situationSelector,
+	flatRulesSelector
+} from 'Selectors/analyseSelectors'
+import { findRuleByDottedName, nestedSituationToPathMap } from 'Engine/rules'
 
 export default compose(
 	reduxForm({
@@ -12,12 +19,29 @@ export default compose(
 		destroyOnUnmount: false,
 		initialValues: { période: 'mois' }
 	}),
-	translate()
-)(function PeriodSwitch() {
+	translate(),
+	connect(
+		state => ({
+			rules: flatRulesSelector(state),
+			situation: nestedSituationToPathMap(situationSelector(state))
+		}),
+		dispatch => ({
+			batchPeriodChange: actions => dispatch(batchActions(actions))
+		})
+	)
+)(function PeriodSwitch({ situation, rules, batchPeriodChange }) {
 	return (
 		<div id="PeriodSwitch">
 			<label>
-				<Field name="période" component="input" type="radio" value="mois" />
+				<Field
+					name="période"
+					component="input"
+					type="radio"
+					value="mois"
+					onChange={e =>
+						updateSituation('mois', batchPeriodChange, situation, rules)
+					}
+				/>
 				<span />
 				<span className="radioText">
 					<Trans>Mois</Trans>
@@ -25,7 +49,15 @@ export default compose(
 			</label>
 			<span style={{ fontSize: '1.5em' }}>{emoji('⏳')}</span>
 			<label>
-				<Field name="période" component="input" type="radio" value="année" />
+				<Field
+					name="période"
+					component="input"
+					type="radio"
+					value="année"
+					onChange={e =>
+						updateSituation('année', batchPeriodChange, situation, rules)
+					}
+				/>
 				<span />
 
 				<span className="radioText">
@@ -35,3 +67,28 @@ export default compose(
 		</div>
 	)
 })
+
+let updateSituation = (toPeriod, batchPeriodChange, situation, rules) => {
+	let needConversation = filter(([dottedName, value]) => {
+		let rule = findRuleByDottedName(rules, dottedName)
+		return value != null && rule.période === 'flexible'
+	})(toPairs(situation))
+	let actions = [
+		...map(
+			([dottedName, value]) =>
+				change(
+					'conversation',
+					dottedName,
+					situation.période === 'mois' && toPeriod === 'année'
+						? value * 12
+						: situation.période === 'année' && toPeriod === 'mois'
+						? value / 12
+						: console.log('oups')
+				),
+			needConversation
+		),
+		change('conversation', 'période', toPeriod)
+	]
+
+	batchPeriodChange(actions)
+}
diff --git a/yarn.lock b/yarn.lock
index cf4da8f0f..c06c4b957 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -7133,6 +7133,10 @@ reduce-reducers@^0.1.2:
   version "0.1.5"
   resolved "https://registry.yarnpkg.com/reduce-reducers/-/reduce-reducers-0.1.5.tgz#ff77ca8068ff41007319b8b4b91533c7e0e54576"
 
+redux-batched-actions@^0.4.1:
+  version "0.4.1"
+  resolved "https://registry.yarnpkg.com/redux-batched-actions/-/redux-batched-actions-0.4.1.tgz#a8de8cef50a1db4f009d5222820c836515597e22"
+
 redux-form@^7.4.2:
   version "7.4.2"
   resolved "https://registry.yarnpkg.com/redux-form/-/redux-form-7.4.2.tgz#d6061088fb682eb9fc5fb9749bd8b102f03154b0"