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diff --git a/date-fns/src/differenceInMonths/index.ts b/date-fns/src/differenceInMonths/index.ts
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+import toDate from '../toDate/index'
+import differenceInCalendarMonths from '../differenceInCalendarMonths/index'
+import compareAsc from '../compareAsc/index'
+import requiredArgs from '../_lib/requiredArgs/index'
+import isLastDayOfMonth from '../isLastDayOfMonth/index'
+
+/**
+ * @name differenceInMonths
+ * @category Month Helpers
+ * @summary Get the number of full months between the given dates.
+ *
+ * @description
+ * Get the number of full months between the given dates.
+ *
+ * ### v2.0.0 breaking changes:
+ *
+ * - [Changes that are common for the whole library](https://github.com/date-fns/date-fns/blob/master/docs/upgradeGuide.md#Common-Changes).
+ *
+ * @param {Date|Number} dateLeft - the later date
+ * @param {Date|Number} dateRight - the earlier date
+ * @returns {Number} the number of full months
+ * @throws {TypeError} 2 arguments required
+ *
+ * @example
+ * // How many full months are between 31 January 2014 and 1 September 2014?
+ * var result = differenceInMonths(new Date(2014, 8, 1), new Date(2014, 0, 31))
+ * //=> 7
+ */
+export default function differenceInMonths(
+  dirtyDateLeft: Date | number,
+  dirtyDateRight: Date | number
+): number {
+  requiredArgs(2, arguments)
+
+  const dateLeft = toDate(dirtyDateLeft)
+  const dateRight = toDate(dirtyDateRight)
+
+  const sign = compareAsc(dateLeft, dateRight)
+  const difference = Math.abs(differenceInCalendarMonths(dateLeft, dateRight))
+  let result
+
+  // Check for the difference of less than month
+  if (difference < 1) {
+    result = 0
+  } else {
+    if (dateLeft.getMonth() === 1 && dateLeft.getDate() > 27) {
+      // This will check if the date is end of Feb and assign a higher end of month date
+      // to compare it with Jan
+      dateLeft.setDate(30)
+    }
+
+    dateLeft.setMonth(dateLeft.getMonth() - sign * difference)
+
+    // Math.abs(diff in full months - diff in calendar months) === 1 if last calendar month is not full
+    // If so, result must be decreased by 1 in absolute value
+    let isLastMonthNotFull = compareAsc(dateLeft, dateRight) === -sign
+
+    // Check for cases of one full calendar month
+    if (
+      isLastDayOfMonth(toDate(dirtyDateLeft)) &&
+      difference === 1 &&
+      compareAsc(dirtyDateLeft, dateRight) === 1
+    ) {
+      isLastMonthNotFull = false
+    }
+
+    result = sign * (difference - Number(isLastMonthNotFull))
+  }
+
+  // Prevent negative zero
+  return result === 0 ? 0 : result
+}