diff --git a/src/cache/cache_line.rs b/src/cache/cache_line.rs
index 33422cc..69f20e9 100644
--- a/src/cache/cache_line.rs
+++ b/src/cache/cache_line.rs
@@ -1,10 +1,15 @@
+use std::rc::Rc;
+
 use chrono::serde::ts_seconds;
-use chrono::{DateTime, Local, Utc};
+use chrono::{DateTime, Datelike, FixedOffset, Local, NaiveDate, TimeDelta, Utc, Weekday};
 use serde::{Deserialize, Serialize};
 
 use crate::models::ExchangeRateResult;
+use crate::Hollidays;
 
-#[derive(Serialize, Deserialize, Debug)]
+const CET: FixedOffset = unsafe { FixedOffset::east_opt(3600).unwrap_unchecked() };
+
+#[derive(Serialize, Deserialize, Debug, PartialEq)]
 pub struct CacheLine {
     #[serde(with = "ts_seconds")]
     date: DateTime<Utc>,
@@ -14,10 +19,63 @@ pub struct CacheLine {
 }
 
 impl CacheLine {
-    pub fn validate(&self) -> bool {
-        let today = Local::now().naive_local().date();
-        let saved = self.date.naive_local().date();
-        saved == today
+    pub fn is_valid(&self) -> bool {
+        self.is_valid_at(Local::now().with_timezone(&CET))
+    }
+
+    pub fn is_valid_at(&self, now_cet: DateTime<FixedOffset>) -> bool {
+        let saved_cet = self.date.with_timezone(&CET);
+
+        // Shortcut: if the saved time is somehow *in the future* vs. 'now', treat as invalid.
+        if saved_cet > now_cet {
+            return false;
+        }
+
+        // This can be optimized, but it won't make a difference for the application
+        let hollidays_opt = if now_cet.year() == saved_cet.year() {
+            Some(Rc::new(Hollidays::new(now_cet.year())))
+        } else {
+            None
+        };
+
+        let mut day_iter = saved_cet.date_naive();
+        let end_day = now_cet.date_naive();
+
+        // Helper: checks if a day is open (ECB publishes).
+        // weekend (Sat/Sun) or holiday is "closed".
+        let is_open_day = |date: NaiveDate| {
+            let wd = date.weekday();
+            let is_weekend = wd == Weekday::Sat || wd == Weekday::Sun;
+
+            let hollidays = hollidays_opt
+                .clone()
+                .unwrap_or_else(|| Rc::new(Hollidays::new(date.year())));
+
+            let is_holiday = hollidays.is_holliday(&date);
+
+            !(is_weekend || is_holiday)
+        };
+
+        while day_iter <= end_day {
+            if is_open_day(day_iter) {
+                // Potential publish time is day_iter at 16:00 CET
+                let publish_time_cet = unsafe {
+                    day_iter
+                        .and_hms_opt(16, 0, 0)
+                        .unwrap_unchecked()
+                        .and_local_timezone(CET)
+                        .unwrap()
+                };
+
+                if publish_time_cet > saved_cet && publish_time_cet <= now_cet {
+                    return false;
+                }
+            }
+            day_iter += TimeDelta::days(1);
+        }
+
+        // If we never found an open day’s 16:00 that invalidates the cache, we're good.
+        true
     }
 
     pub fn new(exchange_rate_results: Vec<ExchangeRateResult>) -> Self {
@@ -28,3 +86,82 @@ impl CacheLine {
         }
     }
 }
+
+impl PartialEq<Vec<ExchangeRateResult>> for CacheLine {
+    fn eq(&self, other: &Vec<ExchangeRateResult>) -> bool {
+        &self.exchange_rate_results == other
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use chrono::TimeZone;
+
+    fn cl(date_utc: DateTime<Utc>) -> CacheLine {
+        CacheLine {
+            date: date_utc,
+            exchange_rate_results: vec![],
+        }
+    }
+
+    #[test]
+    fn test_cache_in_future() {
+        let now_cet = Utc
+            .with_ymd_and_hms(2025, 1, 1, 9, 0, 0)
+            .unwrap()
+            .with_timezone(&CET);
+        let future_utc = Utc.with_ymd_and_hms(2025, 1, 2, 9, 0, 0).unwrap();
+        assert!(!cl(future_utc).is_valid_at(now_cet));
+    }
+
+    #[test]
+    fn test_same_open_day_before_16() {
+        let now_cet = Utc
+            .with_ymd_and_hms(2025, 1, 8, 12, 0, 0)
+            .unwrap()
+            .with_timezone(&CET);
+        let cache_utc = Utc.with_ymd_and_hms(2025, 1, 8, 10, 0, 0).unwrap();
+        assert!(cl(cache_utc).is_valid_at(now_cet));
+    }
+
+    #[test]
+    fn test_same_day_after_16() {
+        let now_cet = Utc
+            .with_ymd_and_hms(2025, 1, 8, 17, 0, 0)
+            .unwrap()
+            .with_timezone(&CET);
+        let cache_utc = Utc.with_ymd_and_hms(2025, 1, 8, 14, 0, 0).unwrap();
+        assert!(!cl(cache_utc).is_valid_at(now_cet));
+    }
+
+    #[test]
+    fn test_saved_after_16_same_day() {
+        let now_cet = Utc
+            .with_ymd_and_hms(2025, 1, 8, 18, 0, 0)
+            .unwrap()
+            .with_timezone(&CET);
+        let cache_utc = Utc.with_ymd_and_hms(2025, 1, 8, 17, 0, 0).unwrap();
+        assert!(cl(cache_utc).is_valid_at(now_cet));
+    }
+
+    #[test]
+    fn test_multi_day_old_cache_should_invalidate_if_open_day_passed() {
+        let now_cet = Utc
+            .with_ymd_and_hms(2025, 1, 10, 18, 0, 0)
+            .unwrap()
+            .with_timezone(&CET);
+        let cache_utc = Utc.with_ymd_and_hms(2025, 1, 5, 10, 0, 0).unwrap();
+        assert!(!cl(cache_utc).is_valid_at(now_cet));
+    }
+
+    #[test]
+    fn test_multi_day_holiday_scenario() {
+        let now_cet = Utc
+            .with_ymd_and_hms(2025, 12, 26, 19, 0, 0)
+            .unwrap()
+            .with_timezone(&CET);
+        let cache_utc = Utc.with_ymd_and_hms(2025, 12, 24, 10, 0, 0).unwrap();
+        assert!(cl(cache_utc).is_valid_at(now_cet));
+    }
+}
diff --git a/src/holiday.rs b/src/holiday.rs
new file mode 100644
index 0000000..3c9a63c
--- /dev/null
+++ b/src/holiday.rs
@@ -0,0 +1,152 @@
+use chrono::{Days, NaiveDate};
+
+/// Calculates the hollidays recognized by the EU
+/// ECB recognizes the following hollidays https://www.ecb.europa.eu/ecb/contacts/working-hours/html/index.en.html
+#[derive(Debug, Clone)]
+pub struct Hollidays {
+    hollidays: [NaiveDate; 15],
+}
+
+impl Hollidays {
+    pub fn is_holliday(&self, date: &NaiveDate) -> bool {
+        self.hollidays.contains(date)
+    }
+
+    pub fn new(year: i32) -> Self {
+        assert!((1583..=4099).contains(&year));
+
+        let easter_sunday = Self::calc_easter_sunday(year);
+        let easter_monday = easter_sunday + Days::new(1);
+        let good_friday = easter_sunday - Days::new(2);
+        let ascension_day = easter_sunday + Days::new(39);
+        let whit_monday = easter_sunday + Days::new(50);
+        let corpus_christi = easter_sunday + Days::new(60);
+        let year_years_day = unsafe { NaiveDate::from_ymd_opt(year, 1, 1).unwrap_unchecked() };
+        let labour_day = unsafe { NaiveDate::from_ymd_opt(year, 5, 1).unwrap_unchecked() };
+        let robert_schuman_declaration =
+            unsafe { NaiveDate::from_ymd_opt(year, 5, 9).unwrap_unchecked() };
+        let german_unity_day = unsafe { NaiveDate::from_ymd_opt(year, 10, 3).unwrap_unchecked() };
+        let all_saints_day = unsafe { NaiveDate::from_ymd_opt(year, 11, 1).unwrap_unchecked() };
+        let christmas_eve = unsafe { NaiveDate::from_ymd_opt(year, 12, 24).unwrap_unchecked() };
+        let christmas_day = unsafe { NaiveDate::from_ymd_opt(year, 12, 25).unwrap_unchecked() };
+        let christmas_holiday = unsafe { NaiveDate::from_ymd_opt(year, 12, 26).unwrap_unchecked() };
+        let new_years_eve = unsafe { NaiveDate::from_ymd_opt(year, 12, 31).unwrap_unchecked() };
+
+        let hollidays = [
+            easter_sunday,
+            easter_monday,
+            good_friday,
+            ascension_day,
+            whit_monday,
+            corpus_christi,
+            year_years_day,
+            labour_day,
+            robert_schuman_declaration,
+            german_unity_day,
+            all_saints_day,
+            christmas_eve,
+            christmas_day,
+            christmas_holiday,
+            new_years_eve,
+        ];
+        Self { hollidays }
+    }
+
+    /// Returns Easter Sunday for a given year (Gregorian calendar).
+    /// This uses a variation of the Butcher's algorithm.
+    /// Valid for years 1583..=4099 in the Gregorian calendar.
+    fn calc_easter_sunday(year: i32) -> NaiveDate {
+        // For reference: https://en.wikipedia.org/wiki/Computus#Butcher's_algorithm
+        let a = year % 19;
+        let b = year / 100;
+        let c = year % 100;
+        let d = b / 4;
+        let e = b % 4;
+        let f = (b + 8) / 25;
+        let g = (b - f + 1) / 3;
+        let h = (19 * a + b - d - g + 15) % 30;
+        let i = c / 4;
+        let k = c % 4;
+        let l = (32 + 2 * e + 2 * i - h - k) % 7;
+        let m = (a + 11 * h + 22 * l) / 451;
+        let month = (h + l - 7 * m + 114) / 31;
+        let day = (h + l - 7 * m + 114) % 31 + 1;
+
+        NaiveDate::from_ymd_opt(year, month as u32, day as u32)
+            .expect("Invalid date calculation for Easter Sunday")
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use chrono::NaiveDate;
+
+    #[test]
+    fn test_holidays_2025() {
+        let year = 2025;
+        let holliday = Hollidays::new(year);
+
+        let easter_sunday_2025 = NaiveDate::from_ymd_opt(2025, 4, 20).unwrap();
+        assert!(
+            holliday.is_holliday(&easter_sunday_2025),
+            "Easter Sunday 2025"
+        );
+
+        let new_years_2025 = NaiveDate::from_ymd_opt(2025, 1, 1).unwrap();
+        assert!(holliday.is_holliday(&new_years_2025), "New Year's Day 2025");
+
+        let labour_day_2025 = NaiveDate::from_ymd_opt(2025, 5, 1).unwrap();
+        assert!(holliday.is_holliday(&labour_day_2025), "Labour Day 2025");
+
+        let random_workday_2025 = NaiveDate::from_ymd_opt(2025, 2, 10).unwrap();
+        assert!(
+            !holliday.is_holliday(&random_workday_2025),
+            "Random weekday 2025"
+        );
+    }
+
+    #[test]
+    fn test_holidays_2026() {
+        let year = 2026;
+        let holliday = Hollidays::new(year);
+
+        let easter_sunday_2026 = NaiveDate::from_ymd_opt(2026, 4, 5).unwrap();
+        assert!(
+            holliday.is_holliday(&easter_sunday_2026),
+            "Easter Sunday 2026"
+        );
+
+        let german_unity_day_2026 = NaiveDate::from_ymd_opt(2026, 10, 3).unwrap();
+        assert!(
+            holliday.is_holliday(&german_unity_day_2026),
+            "Day of German Unity 2026"
+        );
+
+        let random_workday_2026 = NaiveDate::from_ymd_opt(2026, 2, 10).unwrap();
+        assert!(
+            !holliday.is_holliday(&random_workday_2026),
+            "Random weekday 2026"
+        );
+    }
+
+    #[test]
+    #[should_panic]
+    fn test_year_too_low() {
+        disable_panic_stack_trace();
+        let _ = Hollidays::new(1000); 
+    }
+
+    #[test]
+    #[should_panic]
+    fn test_year_too_high() {
+        disable_panic_stack_trace();
+        let _ = Hollidays::new(9999); 
+    }
+
+    fn disable_panic_stack_trace() {
+        std::panic::set_hook(Box::new(|x| {
+            let _ = x;
+        }));
+    }
+}
diff --git a/src/lib.rs b/src/lib.rs
index 81f1f91..8c53513 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,9 +1,12 @@
+pub mod cache;
 pub mod cli;
+mod holiday;
 pub mod models;
 pub mod os;
 pub mod parsing;
 pub mod table;
-pub mod cache;
+
+pub use holiday::Hollidays;
 
 const APP_NAME: &'static str = "ECB-rates";
 
diff --git a/src/main.rs b/src/main.rs
index 88febef..4e128bf 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -45,7 +45,7 @@ async fn main() -> ExitCode {
         || false,
         |c| {
             c.get_cache_line(cli.resolution)
-                .map_or_else(|| false, |cl| cl.validate())
+                .map_or_else(|| false, |cl| cl.is_valid())
         },
     );
     let mut parsed = if cache_ok {
@@ -65,12 +65,24 @@ async fn main() -> ExitCode {
                 return ExitCode::FAILURE;
             }
         };
+
         if !cache_ok {
-            if let Some(cache_safe) = cache.as_mut() {
-                let cache_line = CacheLine::new(parsed.clone());
-                cache_safe.set_cache_line(cli.resolution, cache_line);
-                if let Err(e) = cache_safe.save() {
-                    eprintln!("Failed to save to cache with: {:?}", e);
+            let not_equal_cache = cache.as_ref().map_or_else(
+                || true,
+                |cache_local| {
+                    cache_local
+                        .get_cache_line(cli.resolution)
+                        .map_or_else(|| true, |cache_line| cache_line == &parsed)
+                },
+            );
+
+            if not_equal_cache {
+                if let Some(cache_safe) = cache.as_mut() {
+                    let cache_line = CacheLine::new(parsed.clone());
+                    cache_safe.set_cache_line(cli.resolution, cache_line);
+                    if let Err(e) = cache_safe.save() {
+                        eprintln!("Failed to save to cache with: {:?}", e);
+                    }
                 }
             }
         }
diff --git a/src/models.rs b/src/models.rs
index 3caacf1..2b0dedc 100644
--- a/src/models.rs
+++ b/src/models.rs
@@ -1,7 +1,7 @@
 use serde::{Deserialize, Serialize};
 use std::collections::HashMap;
 
-#[derive(Debug, Serialize, Deserialize, Clone)]
+#[derive(Debug, Serialize, Deserialize, Clone, PartialEq)]
 pub struct ExchangeRateResult {
     pub time: String,
     pub rates: HashMap<String, f64>,