diff --git a/go.mod b/go.mod
index 6ccc10bbc..692056834 100644
--- a/go.mod
+++ b/go.mod
@@ -58,6 +58,7 @@ require (
 	github.com/stretchr/testify v1.7.0
 	github.com/swaggo/swag v1.7.8
 	github.com/ulule/limiter/v3 v3.9.0
+	github.com/vectordotdev/go-datemath v0.1.1-0.20211214182920-0a4ac8742b93 // indirect
 	github.com/yuin/goldmark v1.4.4
 	golang.org/x/crypto v0.0.0-20211215153901-e495a2d5b3d3
 	golang.org/x/image v0.0.0-20211028202545-6944b10bf410
diff --git a/go.sum b/go.sum
index 76b7fbdd1..b30c2a9a6 100644
--- a/go.sum
+++ b/go.sum
@@ -785,6 +785,8 @@ github.com/valyala/fasttemplate v1.2.1 h1:TVEnxayobAdVkhQfrfes2IzOB6o+z4roRkPF52
 github.com/valyala/fasttemplate v1.2.1/go.mod h1:KHLXt3tVN2HBp8eijSv/kGJopbvo7S+qRAEEKiv+SiQ=
 github.com/valyala/tcplisten v0.0.0-20161114210144-ceec8f93295a/go.mod h1:v3UYOV9WzVtRmSR+PDvWpU/qWl4Wa5LApYYX4ZtKbio=
 github.com/valyala/tcplisten v1.0.0/go.mod h1:T0xQ8SeCZGxckz9qRXTfG43PvQ/mcWh7FwZEA7Ioqkc=
+github.com/vectordotdev/go-datemath v0.1.1-0.20211214182920-0a4ac8742b93 h1:bT0ZMfsMi2Xh8dopgxhFT+OJH88QITHpdppdkG1rXJQ=
+github.com/vectordotdev/go-datemath v0.1.1-0.20211214182920-0a4ac8742b93/go.mod h1:PnwzbSst7KD3vpBzzlntZU5gjVa455Uqa5QPiKSYJzQ=
 github.com/xeipuuv/gojsonpointer v0.0.0-20180127040702-4e3ac2762d5f/go.mod h1:N2zxlSyiKSe5eX1tZViRH5QA0qijqEDrYZiPEAiq3wU=
 github.com/xeipuuv/gojsonreference v0.0.0-20180127040603-bd5ef7bd5415/go.mod h1:GwrjFmJcFw6At/Gs6z4yjiIwzuJ1/+UwLxMQDVQXShQ=
 github.com/xeipuuv/gojsonschema v1.2.0/go.mod h1:anYRn/JVcOK2ZgGU+IjEV4nwlhoK5sQluxsYJ78Id3Y=
diff --git a/pkg/integrations/task_collection_test.go b/pkg/integrations/task_collection_test.go
index bbd64c255..e1e11e811 100644
--- a/pkg/integrations/task_collection_test.go
+++ b/pkg/integrations/task_collection_test.go
@@ -17,12 +17,11 @@
 package integrations
 
 import (
-	"net/url"
-	"testing"
-
 	"code.vikunja.io/api/pkg/models"
 	"code.vikunja.io/web/handler"
 	"github.com/stretchr/testify/assert"
+	"net/url"
+	"testing"
 )
 
 func TestTaskCollection(t *testing.T) {
@@ -244,12 +243,37 @@ func TestTaskCollection(t *testing.T) {
 					// the current date.
 					assert.Equal(t, "[]\n", rec.Body.String())
 				})
+				t.Run("unix timestamps", func(t *testing.T) {
+					rec, err := testHandler.testReadAllWithUser(
+						url.Values{
+							"filter_by":         []string{"start_date", "end_date", "due_date"},
+							"filter_value":      []string{"1544500000", "1513164001", "1543500000"},
+							"filter_comparator": []string{"greater", "less", "greater"},
+						},
+						urlParams,
+					)
+					assert.NoError(t, err)
+					assert.NotContains(t, rec.Body.String(), `task #1`)
+					assert.NotContains(t, rec.Body.String(), `task #2`)
+					assert.NotContains(t, rec.Body.String(), `task #3`)
+					assert.NotContains(t, rec.Body.String(), `task #4`)
+					assert.Contains(t, rec.Body.String(), `task #5`)
+					assert.Contains(t, rec.Body.String(), `task #6`)
+					assert.Contains(t, rec.Body.String(), `task #7`)
+					assert.NotContains(t, rec.Body.String(), `task #8`)
+					assert.Contains(t, rec.Body.String(), `task #9`)
+					assert.NotContains(t, rec.Body.String(), `task #10`)
+					assert.NotContains(t, rec.Body.String(), `task #11`)
+					assert.NotContains(t, rec.Body.String(), `task #12`)
+					assert.NotContains(t, rec.Body.String(), `task #13`)
+					assert.NotContains(t, rec.Body.String(), `task #14`)
+				})
 			})
 			t.Run("invalid date", func(t *testing.T) {
 				_, err := testHandler.testReadAllWithUser(
 					url.Values{
 						"filter_by":         []string{"due_date"},
-						"filter_value":      []string{"1540000000"},
+						"filter_value":      []string{"invalid"},
 						"filter_comparator": []string{"greater"},
 					},
 					nil,
@@ -451,7 +475,7 @@ func TestTaskCollection(t *testing.T) {
 				_, err := testHandler.testReadAllWithUser(
 					url.Values{
 						"filter_by":         []string{"due_date"},
-						"filter_value":      []string{"1540000000"},
+						"filter_value":      []string{"invalid"},
 						"filter_comparator": []string{"greater"},
 					},
 					nil,
diff --git a/pkg/models/task_collection_filter.go b/pkg/models/task_collection_filter.go
index 4b8ed1421..0e86a683b 100644
--- a/pkg/models/task_collection_filter.go
+++ b/pkg/models/task_collection_filter.go
@@ -25,6 +25,7 @@ import (
 
 	"code.vikunja.io/api/pkg/config"
 	"github.com/iancoleman/strcase"
+	"github.com/vectordotdev/go-datemath"
 	"xorm.io/xorm/schemas"
 )
 
@@ -159,8 +160,14 @@ func getValueForField(field reflect.StructField, rawValue string) (value interfa
 		value, err = strconv.ParseBool(rawValue)
 	case reflect.Struct:
 		if field.Type == schemas.TimeType {
-			value, err = time.Parse(time.RFC3339, rawValue)
-			value = value.(time.Time).In(config.GetTimeZone())
+			var t datemath.Expression
+			t, err = datemath.Parse(rawValue)
+			if err == nil {
+				value = t.Time(datemath.WithLocation(config.GetTimeZone()))
+			} else {
+				value, err = time.Parse(time.RFC3339, rawValue)
+				value = value.(time.Time).In(config.GetTimeZone())
+			}
 		}
 	case reflect.Slice:
 		// If this is a slice of pointers we're dealing with some property which is a relation