diff --git a/base/src/constants.rs b/base/src/constants.rs
index 0da0afd..53b13f2 100644
--- a/base/src/constants.rs
+++ b/base/src/constants.rs
@@ -18,6 +18,10 @@ pub(crate) const LAST_ROW: i32 = 1_048_576;
 pub(crate) const EXCEL_DATE_BASE: i32 = 693_594;
 
 // Excel can handle dates until the year 0000-01-01
-pub(crate) const EXCEL_DATE_MIN: i32 = -693_959;
+// However, it uses a different numbering scheme for dates
+// that are before 1900-01-01.
+// So for now we will simply not support dates before 1900-01-01.
+pub(crate) const EXCEL_DATE_MIN: i32 = 2;
+
 // Excel can handle dates until the year 9999-12-31
-pub(crate) const EXCEL_DATE_MAX: i32 = 2958465;
+pub(crate) const EXCEL_DATE_MAX: i32 = 2_958_465;
diff --git a/base/src/formatter/dates.rs b/base/src/formatter/dates.rs
index 0705ce0..f4595c1 100644
--- a/base/src/formatter/dates.rs
+++ b/base/src/formatter/dates.rs
@@ -58,11 +58,12 @@ pub fn permissive_date_to_serial_number(day: i32, month: i32, year: i32) -> Resu
     }
 
     date = {
-        let abs_month = month.unsigned_abs();
-        if month <= 0 {
-            date = date - Months::new(abs_month + 1);
+        let month_diff = month - 1;
+        let abs_month = month_diff.unsigned_abs();
+        if month_diff <= 0 {
+            date = date - Months::new(abs_month);
         } else {
-            date = date + Months::new(abs_month - 1);
+            date = date + Months::new(abs_month);
         }
         if !is_date_within_range(date) {
             return Err("Out of range parameters for date".to_string());
@@ -71,11 +72,12 @@ pub fn permissive_date_to_serial_number(day: i32, month: i32, year: i32) -> Resu
     };
 
     date = {
-        let abs_day = day.unsigned_abs() as u64;
-        if day <= 0 {
-            date = date - Days::new(abs_day + 1);
+        let day_diff = day - 1;
+        let abs_day = day_diff.unsigned_abs() as u64;
+        if day_diff <= 0 {
+            date = date - Days::new(abs_day);
         } else {
-            date = date + Days::new(abs_day - 1);
+            date = date + Days::new(abs_day);
         }
         if !is_date_within_range(date) {
             return Err("Out of range parameters for date".to_string());
@@ -108,6 +110,10 @@ mod tests {
             permissive_date_to_serial_number(1, 49, 2000),
             date_to_serial_number(1, 1, 2004)
         );
+        assert_eq!(
+            permissive_date_to_serial_number(1, 49, 2000),
+            date_to_serial_number(1, 1, 2004)
+        );
         assert_eq!(
             permissive_date_to_serial_number(31, 49, 2000),
             date_to_serial_number(31, 1, 2004)
@@ -129,7 +135,7 @@ mod tests {
             Ok(EXCEL_DATE_MAX),
         );
         assert_eq!(
-            permissive_date_to_serial_number(1, 1, 0),
+            permissive_date_to_serial_number(1, 1, 1900),
             Ok(EXCEL_DATE_MIN),
         );
     }
diff --git a/base/src/test/test_date_and_time.rs b/base/src/test/test_date_and_time.rs
index 9fe8fc1..7e6ba03 100644
--- a/base/src/test/test_date_and_time.rs
+++ b/base/src/test/test_date_and_time.rs
@@ -209,7 +209,7 @@ fn test_date_early_dates() {
     );
 
     // This does not agree with Excel, instead of mistakenly allowing
-    // for Feb 29, it will auto-wrap to the next day after Feb 28. 
+    // for Feb 29, it will auto-wrap to the next day after Feb 28.
     assert_eq!(model._get_text("B2"), *"01/03/1900");
 
     // This agrees with Excel from he onward
diff --git a/xlsx/tests/calc_tests/DATE.xlsx b/xlsx/tests/calc_tests/DATE.xlsx
new file mode 100644
index 0000000..711f152
Binary files /dev/null and b/xlsx/tests/calc_tests/DATE.xlsx differ