diff --git a/pkg/models/time_tracking_filter.go b/pkg/models/time_tracking_filter.go
new file mode 100644
index 000000000..ec4c7b68e
--- /dev/null
+++ b/pkg/models/time_tracking_filter.go
@@ -0,0 +1,204 @@
+// Vikunja is a to-do list application to facilitate your life.
+// Copyright 2018-present Vikunja and contributors. All rights reserved.
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+package models
+
+import (
+	"strconv"
+	"strings"
+	"time"
+
+	"code.vikunja.io/api/pkg/config"
+
+	"github.com/ganigeorgiev/fexpr"
+	"github.com/jszwedko/go-datemath"
+	"xorm.io/builder"
+)
+
+// entriesForProjectCond matches time entries belonging to a project given a
+// predicate over a project_id column: standalone entries whose own project_id
+// matches, plus task-attached entries whose task currently lives in a matching
+// project. Tasks move between projects, so the project is resolved via the task
+// at query time rather than denormalized. Used for both permission scoping and
+// the project_id filter.
+func entriesForProjectCond(projectIDCond builder.Cond) builder.Cond {
+	return builder.Or(
+		projectIDCond,
+		builder.In("task_id",
+			builder.Select("id").From("tasks").Where(projectIDCond),
+		),
+	)
+}
+
+// timeEntryFilterCond parses a task-style filter string into a condition over
+// the time_entries table, or nil for an empty filter. Filterable fields:
+// user_id, task_id, project_id (ints / in-lists), start_time, end_time (dates,
+// datemath, or the literal null for running timers). comment is deliberately
+// not filterable — text matching belongs to search.
+func timeEntryFilterCond(filter, filterTimezone string) (builder.Cond, error) {
+	if filter == "" {
+		return nil, nil
+	}
+
+	parsed, err := fexpr.Parse(preprocessFilterString(filter))
+	if err != nil {
+		return nil, &ErrInvalidFilterExpression{Expression: filter, ExpressionError: err}
+	}
+
+	loc := config.GetTimeZone()
+	if filterTimezone != "" {
+		loc, err = time.LoadLocation(filterTimezone)
+		if err != nil {
+			return nil, &ErrInvalidTimezone{Name: filterTimezone, LoadError: err}
+		}
+	}
+
+	return buildTimeEntryFilterCond(parsed, loc)
+}
+
+func buildTimeEntryFilterCond(groups []fexpr.ExprGroup, loc *time.Location) (builder.Cond, error) {
+	conds := make([]builder.Cond, 0, len(groups))
+	joins := make([]taskFilterConcatinator, 0, len(groups))
+
+	for _, g := range groups {
+		join := filterConcatAnd
+		if g.Join == fexpr.JoinOr {
+			join = filterConcatOr
+		}
+
+		var (
+			cond builder.Cond
+			err  error
+		)
+		switch item := g.Item.(type) {
+		case []fexpr.ExprGroup: // a parenthesized sub-expression
+			cond, err = buildTimeEntryFilterCond(item, loc)
+		case fexpr.Expr:
+			var comparator taskFilterComparator
+			comparator, err = getFilterComparatorFromOp(item.Op)
+			if err == nil {
+				cond, err = resolveTimeEntryFilter(item.Left.Literal, comparator, item.Right.Literal, loc)
+			}
+		}
+		if err != nil {
+			return nil, err
+		}
+		conds = append(conds, cond)
+		joins = append(joins, join)
+	}
+
+	if len(conds) == 0 {
+		return nil, nil
+	}
+	result := conds[0]
+	for i := 1; i < len(conds); i++ {
+		if joins[i] == filterConcatOr {
+			result = builder.Or(result, conds[i])
+			continue
+		}
+		result = builder.And(result, conds[i])
+	}
+	return result, nil
+}
+
+func resolveTimeEntryFilter(field string, comparator taskFilterComparator, raw string, loc *time.Location) (builder.Cond, error) {
+	switch field {
+	case "user_id", "task_id":
+		value, err := timeEntryIntFilterValue(raw, comparator)
+		if err != nil {
+			return nil, ErrInvalidTimeEntryFilterValue{Field: field, Value: raw}
+		}
+		return getFilterCond(&taskFilter{field: field, value: value, comparator: comparator, isNumeric: true}, false)
+
+	case "project", "project_id":
+		value, err := timeEntryIntFilterValue(raw, comparator)
+		if err != nil {
+			return nil, ErrInvalidTimeEntryFilterValue{Field: "project_id", Value: raw}
+		}
+		// Build membership positively (standalone-in-project OR task-in-project)
+		// and negate the whole set for != / not in. Negating project_id alone would
+		// wrongly match task-attached entries, whose own project_id is 0.
+		positive, negate := comparator, false
+		if comparator == taskFilterComparatorNotEquals {
+			positive, negate = taskFilterComparatorEquals, true
+		}
+		if comparator == taskFilterComparatorNotIn {
+			positive, negate = taskFilterComparatorIn, true
+		}
+		inner, err := getFilterCond(&taskFilter{field: "project_id", value: value, comparator: positive, isNumeric: true}, false)
+		if err != nil {
+			return nil, err
+		}
+		cond := entriesForProjectCond(inner)
+		if negate {
+			cond = builder.Not{cond}
+		}
+		return cond, nil
+
+	case "start_time", "end_time":
+		if raw == "null" {
+			return nullTimeFilterCond(field, comparator)
+		}
+		value, err := timeEntryTimeFilterValue(raw, loc)
+		if err != nil {
+			return nil, ErrInvalidTimeEntryFilterValue{Field: field, Value: raw}
+		}
+		return getFilterCond(&taskFilter{field: field, value: value, comparator: comparator}, false)
+
+	default:
+		return nil, ErrInvalidTimeEntryFilterField{Field: field}
+	}
+}
+
+// nullTimeFilterCond handles `end_time = null` (running timers) and its negation.
+func nullTimeFilterCond(field string, comparator taskFilterComparator) (builder.Cond, error) {
+	if comparator == taskFilterComparatorEquals {
+		return &builder.IsNull{field}, nil
+	}
+	if comparator == taskFilterComparatorNotEquals {
+		return &builder.NotNull{field}, nil
+	}
+	return nil, ErrInvalidTimeEntryFilterValue{Field: field, Value: "null"}
+}
+
+func timeEntryIntFilterValue(raw string, comparator taskFilterComparator) (any, error) {
+	if comparator == taskFilterComparatorIn || comparator == taskFilterComparatorNotIn {
+		parts := strings.Split(raw, ",")
+		values := make([]int64, 0, len(parts))
+		for _, part := range parts {
+			v, err := strconv.ParseInt(strings.TrimSpace(part), 10, 64)
+			if err != nil {
+				return nil, err
+			}
+			values = append(values, v)
+		}
+		return values, nil
+	}
+	return strconv.ParseInt(strings.TrimSpace(raw), 10, 64)
+}
+
+// timeEntryTimeFilterValue mirrors the task filter's date handling: datemath
+// (now, now-7d) first, then explicit date formats.
+func timeEntryTimeFilterValue(raw string, loc *time.Location) (time.Time, error) {
+	if loc == nil {
+		loc = config.GetTimeZone()
+	}
+	if expr, err := safeDatemathParse(raw); err == nil {
+		t := expr.Time(datemath.WithLocation(loc)).In(config.GetTimeZone())
+		return adjustDateForMysql(t), nil
+	}
+	return parseTimeFromUserInput(raw, loc)
+}