diff --git a/CHANGELOG.md b/CHANGELOG.md
index a1859b6..711baec 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,11 @@ Versioning].
 
 ## [Unreleased] <!-- #release:date -->
 
+* Add `invoice_number`, `currency`, `issued_at`, and `metadata` fields to the
+  `Invoice`.
+* Fix issue where `get_customer_costs` queries would fail when provided
+  timeframe filters with non-UTC offsets.
+
 ## [0.9.0] - 2024-01-17
 
 * Support `additional_emails` field on `Customer`.
diff --git a/src/client/customers.rs b/src/client/customers.rs
index 7432379..35728fe 100644
--- a/src/client/customers.rs
+++ b/src/client/customers.rs
@@ -21,7 +21,7 @@ use reqwest::{Method, RequestBuilder};
 use serde::{Deserialize, Serialize};
 use serde_enum_str::{Deserialize_enum_str, Serialize_enum_str};
 use time::format_description::well_known::Rfc3339;
-use time::OffsetDateTime;
+use time::{OffsetDateTime, UtcOffset};
 
 use crate::client::taxes::{TaxId, TaxIdRequest};
 use crate::client::Client;
@@ -481,10 +481,24 @@ impl Filterable<CustomerCostParamsFilter<'_>> for RequestBuilder {
             self = self.query(&[("group_by", group_by)]);
         }
         if let Some(timeframe_start) = &filter.timeframe_start {
-            self = self.query(&[("timeframe_start", timeframe_start.format(&Rfc3339).unwrap())]);
+            self = self.query(&[(
+                "timeframe_start",
+                timeframe_start
+                    // Orb requires supplied datetimes be in UTC
+                    .to_offset(UtcOffset::UTC)
+                    .format(&Rfc3339)
+                    .unwrap(),
+            )]);
         }
         if let Some(timeframe_end) = &filter.timeframe_end {
-            self = self.query(&[("timeframe_end", timeframe_end.format(&Rfc3339).unwrap())]);
+            self = self.query(&[(
+                "timeframe_end",
+                timeframe_end
+                    // Orb requires supplied datetimes be in UTC
+                    .to_offset(UtcOffset::UTC)
+                    .format(&Rfc3339)
+                    .unwrap(),
+            )]);
         }
         self
     }
diff --git a/src/client/invoices.rs b/src/client/invoices.rs
index b3fb1cd..7ee9ab3 100644
--- a/src/client/invoices.rs
+++ b/src/client/invoices.rs
@@ -13,6 +13,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+use std::collections::BTreeMap;
+
 use futures_core::Stream;
 use reqwest::Method;
 use serde::{Deserialize, Serialize};
@@ -38,8 +40,12 @@ pub struct Invoice {
     /// The issue date of the invoice.
     #[serde(with = "time::serde::rfc3339")]
     pub invoice_date: OffsetDateTime,
+    /// An automatically generated number to help track and reconcile invoices.
+    pub invoice_number: String,
     /// The link to download the PDF representation of the invoice.
     pub invoice_pdf: Option<String>,
+    /// An ISO 4217 currency string, or "credits"
+    pub currency: String,
     /// The total after any minimums, discounts, and taxes have been applied.
     pub total: String,
     /// This is the final amount required to be charged to the
@@ -49,10 +55,17 @@ pub struct Invoice {
     /// The time at which the invoice was created.
     #[serde(with = "time::serde::rfc3339")]
     pub created_at: OffsetDateTime,
+    /// The time at which the invoice was issued.
+    #[serde(with = "time::serde::rfc3339::option")]
+    pub issued_at: Option<OffsetDateTime>,
     /// The link to the hosted invoice
     pub hosted_invoice_url: Option<String>,
     /// The status (see [`InvoiceStatusFilter`] for details)
     pub status: String,
+    /// Arbitrary metadata that is attached to the invoice. Cannot be nested, must have string
+    /// values.
+    #[serde(default)]
+    pub metadata: BTreeMap<String, String>,
     // TODO: many missing fields.
 }