diff --git a/web/src/endpoints/availability/get_new.rs b/web/src/endpoints/availability/get_new.rs
index b5a73dad..43dd1a48 100644
--- a/web/src/endpoints/availability/get_new.rs
+++ b/web/src/endpoints/availability/get_new.rs
@@ -6,9 +6,10 @@ use sqlx::PgPool;
 
 use crate::endpoints::availability::NewOrEditAvailabilityTemplate;
 use crate::models::{
-    find_free_time_slots, only_one_availability_exists_and_is_whole_day, Availability, User,
+    find_free_time_slots, only_one_availability_exists_and_is_whole_day, Availability, AvailabilityTime, User
 };
 use crate::utils::ApplicationError;
+use crate::{END_OF_DAY, START_OF_DAY};
 
 #[derive(Deserialize)]
 struct AvailabilityNewQuery {
@@ -27,20 +28,25 @@ pub async fn get(
         Availability::read_by_user_and_date(pool.get_ref(), user.id, &query.date).await?;
     let free_slots = find_free_time_slots(&availabilities_from_user);
 
-    let user_can_create_availabillity =
-        !(only_one_availability_exists_and_is_whole_day(&availabilities_from_user)
-            || free_slots.len() == 0);
+    let user_can_create_availabillity = availabilities_from_user.len() == 0
+        || !only_one_availability_exists_and_is_whole_day(&availabilities_from_user)
+        || free_slots.len() > 0;
 
     if !user_can_create_availabillity {
         return Ok(HttpResponse::BadRequest().finish());
     }
 
+    let time_selection = if query.whole_day.unwrap_or(true) {
+        AvailabilityTime::WholeDay
+    } else {
+        AvailabilityTime::Temporarily(START_OF_DAY, END_OF_DAY)
+    };
+
     let template = NewOrEditAvailabilityTemplate {
         user: user.into_inner(),
         date: query.date,
-        whole_day_selected: query.whole_day.unwrap_or(true),
+        time_selection,
         id: None,
-        time: None,
         comment: None,
         slot_suggestions: free_slots,
     };
diff --git a/web/src/endpoints/availability/get_overview.rs b/web/src/endpoints/availability/get_overview.rs
index d83d383b..51c07254 100644
--- a/web/src/endpoints/availability/get_overview.rs
+++ b/web/src/endpoints/availability/get_overview.rs
@@ -71,10 +71,15 @@ async fn get(
 
     let availabilities_from_user =
         Availability::read_by_user_and_date(pool.get_ref(), user.id, &date).await?;
+    println!("{availabilities_from_user:#?}");
 
-    let user_can_create_availabillity =
-        !(only_one_availability_exists_and_is_whole_day(&availabilities_from_user)
-            || find_free_time_slots(&availabilities_from_user).len() == 0);
+    let user_can_create_availabillity = availabilities_from_user.len() == 0
+        || !only_one_availability_exists_and_is_whole_day(&availabilities_from_user)
+        || find_free_time_slots(&availabilities_from_user).len() > 0;
+
+    println!("{} || {} || {} = {user_can_create_availabillity}", availabilities_from_user.len() == 0,
+        !only_one_availability_exists_and_is_whole_day(&availabilities_from_user),
+        find_free_time_slots(&availabilities_from_user).len() > 0);
 
     let mut events_and_assignments = Vec::new();
     for e in Event::read_all_by_date_and_area_including_location(
diff --git a/web/src/endpoints/availability/get_update.rs b/web/src/endpoints/availability/get_update.rs
index 54d69aab..18016a3a 100644
--- a/web/src/endpoints/availability/get_update.rs
+++ b/web/src/endpoints/availability/get_update.rs
@@ -33,8 +33,6 @@ pub async fn get(
         return Err(ApplicationError::Unauthorized);
     }
 
-    let whole_day_selected = query.whole_day.unwrap_or(availability.time == AvailabilityTime::WholeDay);
-
     let suggestions = if let AvailabilityTime::Temporarily(start, end) = availability.time {
         let availabilities = Availability::read_by_user_and_date(
             pool.get_ref(),
@@ -51,14 +49,20 @@ pub async fn get(
         Vec::new()
     };
 
+    let time_selection = if query.whole_day.unwrap_or(availability.time == AvailabilityTime::WholeDay) {
+        AvailabilityTime::WholeDay
+    } else {
+        availability.time.clone()
+    };
+
+    println!("{:?}", availability.time);
     let template = NewOrEditAvailabilityTemplate {
         user: user.into_inner(),
         date: availability.date,
         id: Some(path.id),
-        time: Some(availability.time),
+        time_selection,
         comment: availability.comment.as_deref(),
         slot_suggestions: suggestions,
-        whole_day_selected
     };
 
     Ok(HttpResponse::Ok().body(template.render()?))
diff --git a/web/src/endpoints/availability/mod.rs b/web/src/endpoints/availability/mod.rs
index f2d47a06..c6e5dfbf 100644
--- a/web/src/endpoints/availability/mod.rs
+++ b/web/src/endpoints/availability/mod.rs
@@ -2,7 +2,7 @@ use chrono::{NaiveDate, NaiveTime};
 use rinja::Template;
 
 use crate::filters;
-use crate::models::{AvailabilityTime, Role, User};
+use crate::models::{Availability, AvailabilityChangeset, AvailabilityTime, Role, User};
 
 pub mod delete;
 pub mod get_new;
@@ -17,8 +17,30 @@ struct NewOrEditAvailabilityTemplate<'a> {
     user: User,
     date: NaiveDate,
     id: Option<i32>,
-    time: Option<AvailabilityTime>,
-    whole_day_selected: bool,
+    time_selection: AvailabilityTime,
     comment: Option<&'a str>,
     slot_suggestions: Vec<(NaiveTime, NaiveTime)>,
 }
+
+fn find_adjacend_availability<'a>(
+    changeset: &AvailabilityChangeset,
+    availability_id_to_be_updated: Option<i32>,
+    existing_availabilities: &'a [Availability],
+) -> Option<&'a Availability> {
+    let AvailabilityTime::Temporarily(changeset_start, changeset_end) = changeset.time else {
+        return None;
+    };
+
+    for a in existing_availabilities
+        .iter()
+        .filter(|a| availability_id_to_be_updated.is_none_or(|id| a.id != id))
+    {
+        if let AvailabilityTime::Temporarily(start, end) = a.time {
+            if start == changeset_end || end == changeset_start {
+                return Some(a);
+            }
+        }
+    }
+
+    None
+}
diff --git a/web/src/endpoints/availability/post_new.rs b/web/src/endpoints/availability/post_new.rs
index 2f99bf95..f5a8660f 100644
--- a/web/src/endpoints/availability/post_new.rs
+++ b/web/src/endpoints/availability/post_new.rs
@@ -1,10 +1,12 @@
 use actix_web::{http::header::LOCATION, web, HttpResponse, Responder};
 use chrono::{NaiveDate, NaiveTime};
+use garde::Validate;
 use serde::Deserialize;
 use sqlx::PgPool;
 
 use crate::{
-    models::{Availability, User},
+    endpoints::availability::find_adjacend_availability,
+    models::{Availability, AvailabilityChangeset, AvailabilityContext, AvailabilityTime, User},
     utils::{self, ApplicationError},
 };
 
@@ -22,16 +24,43 @@ pub async fn post(
     pool: web::Data<PgPool>,
     form: web::Form<AvailabillityForm>,
 ) -> Result<impl Responder, ApplicationError> {
-    // TODO: create and validate changeset
-    //Availability::create(
-    //    pool.get_ref(),
-    //    user.id,
-    //    form.date,
-    //    form.from,
-    //    form.till,
-    //    form.comment.clone(),
-    //)
-    //.await?;
+    let existing_availabilities =
+        Availability::read_by_user_and_date(pool.get_ref(), user.id, &form.date).await?;
+    let context = AvailabilityContext {
+        existing_availabilities: existing_availabilities.clone(),
+    };
+
+    let time = if form.from.is_some() && form.till.is_some() {
+        AvailabilityTime::Temporarily(form.from.unwrap(), form.till.unwrap())
+    } else {
+        AvailabilityTime::WholeDay
+    };
+
+    let mut changeset = AvailabilityChangeset {
+        time,
+        comment: form.comment.clone(),
+    };
+
+    if let Err(e) = changeset.validate_with(&context) {
+        return Ok(HttpResponse::BadRequest().body(e.to_string()));
+    };
+
+    if let Some(a) = find_adjacend_availability(&changeset, None, &existing_availabilities) {
+        let (changeset_start, changeset_end) = changeset.time.time_tuple_opt().unwrap();
+        let (adjacent_start, adjacent_end) = changeset.time.time_tuple_opt().unwrap();
+
+        if adjacent_end == changeset_start {
+            changeset.time = AvailabilityTime::Temporarily(adjacent_start, changeset_end);
+        }
+
+        if adjacent_start == changeset_end {
+            changeset.time = AvailabilityTime::Temporarily(changeset_start, adjacent_end);
+        }
+
+        Availability::update(pool.get_ref(), a.id, changeset).await?;
+    } else {
+        Availability::create(pool.get_ref(), user.id, form.date, changeset).await?;
+    }
 
     let url = utils::get_return_url_for_date(&form.date);
     Ok(HttpResponse::Found()
diff --git a/web/src/endpoints/availability/post_update.rs b/web/src/endpoints/availability/post_update.rs
index 28b647a4..ea1ab9d2 100644
--- a/web/src/endpoints/availability/post_update.rs
+++ b/web/src/endpoints/availability/post_update.rs
@@ -3,7 +3,7 @@ use garde::Validate;
 use sqlx::PgPool;
 
 use crate::{
-    endpoints::{availability::post_new::AvailabillityForm, IdPath},
+    endpoints::{availability::{find_adjacend_availability, post_new::AvailabillityForm}, IdPath},
     models::{Availability, AvailabilityChangeset, AvailabilityContext, AvailabilityTime, User},
     utils::{self, ApplicationError},
 };
@@ -44,22 +44,7 @@ pub async fn post(
         return Ok(HttpResponse::BadRequest().body(e.to_string()));
     };
 
-    let mut adjacent = None;
-    if let AvailabilityTime::Temporarily(changeset_start, changeset_end) = changeset.time {
-        for a in existing_availabilities
-            .iter()
-            .filter(|a| a.id != availability.id)
-        {
-            if let AvailabilityTime::Temporarily(start, end) = a.time {
-                if start == changeset_end || end == changeset_start {
-                    adjacent = Some(a);
-                    break;
-                }
-            }
-        }
-    }
-
-    if let Some(a) = adjacent {
+    if let Some(a) = find_adjacend_availability(&changeset, Some(availability.id), &existing_availabilities) {
         let (changeset_start, changeset_end) = changeset.time.time_tuple_opt().unwrap();
         let (adjacent_start, adjacent_end) = changeset.time.time_tuple_opt().unwrap();
 
diff --git a/web/src/models/availability_changeset.rs b/web/src/models/availability_changeset.rs
index 93d33700..627a6a2b 100644
--- a/web/src/models/availability_changeset.rs
+++ b/web/src/models/availability_changeset.rs
@@ -34,7 +34,7 @@ fn time_is_not_already_made_available(
             return Err(garde::Error::new("cant create a availability while an other availability for the whole day is already present"));
         }
 
-        if find_free_time_slots(&context.existing_availabilities).len() == 0 {
+        if context.existing_availabilities.len() > 0 && find_free_time_slots(&context.existing_availabilities).len() == 0 {
             return Err(garde::Error::new(
                 "cant create a availability as every time slot is already filled",
             ));
@@ -71,7 +71,7 @@ pub fn find_free_time_slots(availabilities: &[Availability]) -> Vec<(NaiveTime,
     if times.len() == 0 {
         return Vec::new();
     }
-    //println!("zeiten {times:?}");
+    println!("zeiten {times:?}");
 
     times.sort();
 
diff --git a/web/templates/availability/new_or_edit.html b/web/templates/availability/new_or_edit.html
index 198f9601..4c3d7f32 100644
--- a/web/templates/availability/new_or_edit.html
+++ b/web/templates/availability/new_or_edit.html
@@ -12,6 +12,7 @@
         {% endif %}
 
         <input type="hidden" name="date" value="{{ date }}">
+        {% let whole_day_selected = time_selection == AvailabilityTime::WholeDay %}
 
         <div class="field is-horizontal">
           <div class="field-label">
@@ -46,25 +47,21 @@
             <label class="label">Von - Bis</label>
           </div>
           <div class="field-body">
-            {% let times = ("00:00".to_string(), "23:59".to_string()) -%}
-            {% if let Some(times) = time -%}
-            {% if let AvailabilityTime::Temporarily(start, end) = times -%}
-            {% let times = (start.to_string(), end.to_string()) -%}
-            {% endif -%}
-            {% endif -%}
+            {% let times = time_selection.time_tuple() -%}
             <div class="field">
-              <input class="input" type="time" id="from" name="from" value='{{ times.0 }}' {{
+              <input class="input" type="time" id="from" name="from" value='{{ times.0.format("%R") }}' {{
                 whole_day_selected|cond_show("disabled") }} {{ whole_day_selected|invert|ref|cond_show("required") }}>
-
+              {% if slot_suggestions.len() > 0 %}
               <p class="help">noch mögliche Zeiträume:</p>
               <div class="tags help">
                 {% for (s, e) in slot_suggestions %}
                 <span class="tag">{{ s }} - {{ e }}</span>
                 {% endfor %}
               </div>
+              {% endif %}
             </div>
             <div class="field">
-              <input class="input" type="time" id="till" name="till" value='{{ times.1 }}' {{
+              <input class="input" type="time" id="till" name="till" value='{{ times.1.format("%R") }}' {{
                 whole_day_selected|cond_show("disabled") }} {{ whole_day_selected|invert|ref|cond_show("required") }}>
             </div>
           </div>