diff --git a/internal/controllers/subscriptions.go b/internal/controllers/subscriptions.go
index fdbc7c6..74ad69a 100644
--- a/internal/controllers/subscriptions.go
+++ b/internal/controllers/subscriptions.go
@@ -113,13 +113,8 @@ func (sa *SubscriptionAdder) AddSubscription(tx *gorm.DB, req model.Subscription
 		return sa.subscriptionError(*username, err.Error())
 	}
 
-	// Define the subscription options.
-	opts := &model.SubscriptionOptions{
-		Paid: paid,
-	}
-
 	// Add the subscription.
-	sub, err := db.SubscribeUserToPlan(sa.cfg.Ctx, tx, user, plan, opts)
+	sub, err := db.SubscribeUserToPlan(sa.cfg.Ctx, tx, user, plan, &req.SubscriptionOptions)
 	if err != nil {
 		log.Error(err)
 		return sa.subscriptionError(*username, err.Error())
diff --git a/internal/controllers/users.go b/internal/controllers/users.go
index 2bc2284..719f879 100644
--- a/internal/controllers/users.go
+++ b/internal/controllers/users.go
@@ -13,6 +13,7 @@ import (
 	"github.com/cyverse/QMS/internal/db"
 	"github.com/cyverse/QMS/internal/httpmodel"
 	"github.com/cyverse/QMS/internal/model"
+	"github.com/cyverse/QMS/internal/model/timestamp"
 	"github.com/cyverse/QMS/internal/query"
 	"github.com/labstack/echo/v4"
 	"github.com/sirupsen/logrus"
@@ -403,10 +404,11 @@ func (s Server) UpdateSubscription(ctx echo.Context) error {
 		log.Debug("deactivated all active plans for the user")
 
 		// Define the subscription options.
+		endTimestamp := timestamp.Timestamp(endDate)
 		opts := &model.SubscriptionOptions{
 			Paid:    &paid,
 			Periods: &periods,
-			EndDate: &endDate,
+			EndDate: &endTimestamp,
 		}
 
 		// Subscribe the user to the plan.
diff --git a/internal/model/subscriptions.go b/internal/model/subscriptions.go
index f116cb8..8918eee 100644
--- a/internal/model/subscriptions.go
+++ b/internal/model/subscriptions.go
@@ -1,6 +1,10 @@
 package model
 
-import "time"
+import (
+	"time"
+
+	"github.com/cyverse/QMS/internal/model/timestamp"
+)
 
 // SubscriptionOptions represents options that can be applied to a new subscription.
 //
@@ -13,7 +17,7 @@ type SubscriptionOptions struct {
 	Periods *int32 `json:"periods"`
 
 	// The effective end date of the subscription.
-	EndDate *time.Time `json:"end_date"`
+	EndDate *timestamp.Timestamp `json:"end_date"`
 }
 
 // Return the appropriate paid flag for the subscription options.
@@ -39,7 +43,7 @@ func (o *SubscriptionOptions) GetEndDate(startDate time.Time) time.Time {
 	if o.EndDate == nil {
 		return startDate.AddDate(int(o.GetPeriods()), 0, 0)
 	} else {
-		return *o.EndDate
+		return time.Time(*o.EndDate)
 	}
 }
 
@@ -47,6 +51,8 @@ func (o *SubscriptionOptions) GetEndDate(startDate time.Time) time.Time {
 //
 // swagger: model
 type SubscriptionRequest struct {
+	SubscriptionOptions
+
 	// The username to associate with the subscription
 	//
 	// required: true
@@ -56,9 +62,6 @@ type SubscriptionRequest struct {
 	//
 	// required: true
 	PlanName *string `json:"plan_name"`
-
-	// True if the user paid for the subscription.
-	Paid *bool `json:"paid"`
 }
 
 // SubscriptionRequests represents a list of subscription requests.
diff --git a/internal/model/timestamp/timestamp.go b/internal/model/timestamp/timestamp.go
new file mode 100644
index 0000000..54fc50f
--- /dev/null
+++ b/internal/model/timestamp/timestamp.go
@@ -0,0 +1,78 @@
+package timestamp
+
+import (
+	"fmt"
+	"regexp"
+	"strconv"
+	"time"
+)
+
+const (
+	DateOnly      = time.DateOnly
+	DateTimeLocal = "2006-01-02T15:04:05"
+	RFC3339       = time.RFC3339
+)
+
+var (
+	DateOnlyRegexp      = regexp.MustCompile(`^\d{4}-\d{2}-\d{2}$`)
+	DateTimeLocalRegexp = regexp.MustCompile(`^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}$`)
+	RFC3339Regexp       = regexp.MustCompile(`^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}(Z|[+-]\d{2}:\d{2})$`)
+)
+
+// Timestamp is an alias for time.Time with lenient parsing in the local time zone by default.
+type Timestamp time.Time
+
+// layoutForValue returns the layout to use for a given timestamp value.
+func layoutForValue(value string) (string, error) {
+	switch {
+	case DateOnlyRegexp.MatchString(value):
+		return DateOnly, nil
+	case DateTimeLocalRegexp.MatchString(value):
+		return DateTimeLocal, nil
+	case RFC3339Regexp.MatchString(value):
+		return RFC3339, nil
+	default:
+		return "", fmt.Errorf("unrecognized timestamp layout: %s", value)
+	}
+}
+
+// Parse attempts to parse the given value as a timestamp. The timestamp will be parsed in the time zone of the
+// current location unless the time zone is included in the timestamp itself. The accepted formats are:
+//
+//	2024-02-21                - Midnight on the specified date in the local time zone.
+//	2024-02-21T01:02:03       - The specified date and time in the local time zone.
+//	2024-02-21T01:02:03Z      - The specified date and time in UTC.
+//	2024-02-01T01:02:03-07:00 - The specified date and time in the specified time zone.
+func Parse(value string) (Timestamp, error) {
+	var t time.Time
+
+	// Determine the timestamp layout.
+	layout, err := layoutForValue(value)
+	if err != nil {
+		return Timestamp(t), err
+	}
+
+	// Parse the timestamp.
+	t, err = time.ParseInLocation(layout, value, time.Now().Location())
+	return Timestamp(t), err
+}
+
+// UnmarshalJSON converts a JSON to a timestamp.
+func (t *Timestamp) UnmarshalJSON(data []byte) error {
+	value := string(data)
+
+	// Ignore empty values.
+	if value == "null" || value == `""` {
+		return nil
+	}
+
+	// Unquote the string.
+	value, err := strconv.Unquote(value)
+	if err != nil {
+		return err
+	}
+
+	// Parse the timestamp.
+	*t, err = Parse(value)
+	return err
+}