diff --git a/src/api/compress.rs b/src/api/compress.rs
index 220cd92..ad93f71 100644
--- a/src/api/compress.rs
+++ b/src/api/compress.rs
@@ -299,12 +299,15 @@ async fn compress_json(
         } else {
             (saved_bytes as f64) * 100.0 / (original_size as f64)
         };
-        let skip_charge = req.compression_rate == Some(100)
-            && req.target_size_bytes.is_none()
-            && format_in == format_out
-            && req.max_width.is_none()
-            && req.max_height.is_none();
-        let charge_units = anonymous_reserved || (!skip_charge && compressed_size < original_size);
+        let charge_units = anonymous_reserved
+            || quota::output_consumes_unit(
+                req.compression_rate,
+                format_in == format_out,
+                req.max_width.is_some() || req.max_height.is_some(),
+                req.target_size_bytes.is_some(),
+                original_size,
+                compressed_size,
+            );
 
         let task_id = Uuid::new_v4();
         let file_id = Uuid::new_v4();
@@ -583,12 +586,14 @@ async fn compress_direct(
         } else {
             (saved_bytes as f64) * 100.0 / (original_size as f64)
         };
-        let skip_charge = req.compression_rate == Some(100)
-            && req.target_size_bytes.is_none()
-            && format_in == format_out
-            && req.max_width.is_none()
-            && req.max_height.is_none();
-        let charge_units = !skip_charge && compressed_size < original_size;
+        let charge_units = quota::output_consumes_unit(
+            req.compression_rate,
+            format_in == format_out,
+            req.max_width.is_some() || req.max_height.is_some(),
+            req.target_size_bytes.is_some(),
+            original_size,
+            compressed_size,
+        );
 
         let task_id = Uuid::new_v4();
         let file_id = Uuid::new_v4();
diff --git a/src/services/quota.rs b/src/services/quota.rs
index cd39879..06f35f2 100644
--- a/src/services/quota.rs
+++ b/src/services/quota.rs
@@ -451,7 +451,8 @@ pub async fn settle_anonymous_task_reservation(
                    AND f.status = 'completed'
                    AND f.compressed_size < f.original_size
                    AND NOT (
-                     tasks.compression_rate = 100
+                     -- NULL means the caller did not request the explicit 100% passthrough.
+                     COALESCE(tasks.compression_rate = 100, false)
                      AND f.original_format = f.output_format
                      AND tasks.max_width IS NULL
                      AND tasks.max_height IS NULL
@@ -514,6 +515,19 @@ pub async fn settle_anonymous_task_reservation(
     Ok(Some(refundable))
 }
 
+pub(crate) fn output_consumes_unit(
+    compression_rate: Option<u8>,
+    same_format: bool,
+    has_resize: bool,
+    has_target_size: bool,
+    original_size: u64,
+    output_size: u64,
+) -> bool {
+    let is_unmetered_passthrough =
+        compression_rate == Some(100) && same_format && !has_resize && !has_target_size;
+    !is_unmetered_passthrough && output_size < original_size
+}
+
 fn refundable_reserved_units(reserved: i32, total_files: i32, consumed_units: i32) -> u32 {
     let reserved = reserved.max(0);
     let total_files = total_files.max(0);
@@ -556,6 +570,125 @@ fn utc8_date() -> NaiveDate {
 #[cfg(test)]
 mod tests {
     use super::*;
+    use crate::config::Config;
+    use crate::services::mail::Mailer;
+    use sqlx::postgres::PgPoolOptions;
+    use std::sync::Arc;
+    use tokio::sync::Semaphore;
+
+    struct AnonymousSettlementFixture<'a> {
+        session_id: &'a str,
+        ip: IpAddr,
+        date: NaiveDate,
+        reserved_units: u32,
+        compression_rate: Option<i16>,
+        total_files: usize,
+        completed_files: usize,
+    }
+
+    async fn build_test_state(
+        pool: sqlx::PgPool,
+        database_url: String,
+        redis_url: String,
+    ) -> AppState {
+        let mut config = Config::from_env().expect("load quota test config");
+        config.database_url = database_url;
+        config.redis_url = redis_url;
+        config.mail_enabled = false;
+        config.mail_log_links_when_disabled = false;
+        config.anon_daily_units = 10;
+        let redis = redis::Client::open(config.redis_url.clone())
+            .expect("create quota test Redis client")
+            .get_connection_manager()
+            .await
+            .expect("connect quota test Redis");
+        AppState {
+            mailer: Arc::new(Mailer::new(&config).expect("create disabled quota test mailer")),
+            image_processing_semaphore: Arc::new(Semaphore::new(2)),
+            runtime_policy_cache: crate::services::settings::RuntimePolicyCache::new(),
+            storage_cache: crate::services::storage::StorageCache::new(),
+            config,
+            db: pool,
+            redis,
+        }
+    }
+
+    async fn insert_anonymous_settlement_fixture(
+        pool: &sqlx::PgPool,
+        fixture: AnonymousSettlementFixture<'_>,
+    ) -> Uuid {
+        assert!(fixture.completed_files <= fixture.total_files);
+        let task_id = Uuid::new_v4();
+        sqlx::query(
+            r#"
+            INSERT INTO tasks (
+              id, session_id, client_ip, status,
+              compression_rate, total_files, completed_files, failed_files,
+              anonymous_units_reserved, anonymous_quota_date
+            ) VALUES (
+              $1, $2, $3::inet, 'completed',
+              $4, $5, $6, $7,
+              $8, $9
+            )
+            "#,
+        )
+        .bind(task_id)
+        .bind(fixture.session_id)
+        .bind(fixture.ip.to_string())
+        .bind(fixture.compression_rate)
+        .bind(fixture.total_files as i32)
+        .bind(fixture.completed_files as i32)
+        .bind((fixture.total_files - fixture.completed_files) as i32)
+        .bind(fixture.reserved_units as i32)
+        .bind(fixture.date)
+        .execute(pool)
+        .await
+        .expect("insert anonymous settlement task");
+
+        for index in 0..fixture.total_files {
+            let completed = index < fixture.completed_files;
+            sqlx::query(
+                r#"
+                INSERT INTO task_files (
+                  id, task_id, original_name, original_format, output_format,
+                  original_size, compressed_size, status
+                ) VALUES (
+                  $1, $2, $3, 'jpeg', 'jpeg',
+                  100, $4, $5::file_status
+                )
+                "#,
+            )
+            .bind(Uuid::new_v4())
+            .bind(task_id)
+            .bind(format!("fixture-{index}.jpg"))
+            .bind(completed.then_some(50_i64))
+            .bind(if completed { "completed" } else { "failed" })
+            .execute(pool)
+            .await
+            .expect("insert anonymous settlement file");
+        }
+        task_id
+    }
+
+    async fn anonymous_quota_counts(
+        state: &AppState,
+        session_id: &str,
+        ip: IpAddr,
+        date: NaiveDate,
+    ) -> (i64, i64) {
+        let mut redis = state.redis.clone();
+        let session_count: Option<i64> = redis::cmd("GET")
+            .arg(anonymous_session_key(session_id, date))
+            .query_async(&mut redis)
+            .await
+            .expect("read anonymous session quota");
+        let ip_count: Option<i64> = redis::cmd("GET")
+            .arg(anonymous_ip_key(ip, date))
+            .query_async(&mut redis)
+            .await
+            .expect("read anonymous IP quota");
+        (session_count.unwrap_or(0), ip_count.unwrap_or(0))
+    }
 
     #[test]
     fn balance_keeps_redeemed_units_separate_from_plan_usage() {
@@ -606,6 +739,29 @@ mod tests {
         assert_eq!(refundable_reserved_units(10, -1, -2), 0);
     }
 
+    #[test]
+    fn output_metering_matches_passthrough_contract() {
+        assert!(output_consumes_unit(None, true, false, false, 100, 50));
+        assert!(!output_consumes_unit(
+            Some(100),
+            true,
+            false,
+            false,
+            100,
+            50
+        ));
+        assert!(output_consumes_unit(
+            Some(100),
+            false,
+            false,
+            false,
+            100,
+            50
+        ));
+        assert!(output_consumes_unit(Some(100), true, true, false, 100, 50));
+        assert!(!output_consumes_unit(None, true, false, false, 100, 100));
+    }
+
     #[test]
     fn anonymous_quota_keys_use_the_reserved_date() {
         let date = NaiveDate::from_ymd_opt(2026, 7, 25).unwrap();
@@ -633,4 +789,194 @@ mod tests {
             "203.0.113.7"
         );
     }
+
+    #[tokio::test(flavor = "multi_thread", worker_threads = 4)]
+    #[ignore = "requires isolated IMAGEFORGE_TEST_DATABASE_URL and IMAGEFORGE_TEST_REDIS_URL"]
+    async fn anonymous_batch_settlement_charges_successes_and_refunds_only_unused_units() {
+        let database_url = std::env::var("IMAGEFORGE_TEST_DATABASE_URL")
+            .expect("IMAGEFORGE_TEST_DATABASE_URL must be set");
+        assert!(
+            database_url.to_ascii_lowercase().contains("test"),
+            "refusing to run destructive integration test outside a test database"
+        );
+        let redis_url = std::env::var("IMAGEFORGE_TEST_REDIS_URL")
+            .expect("IMAGEFORGE_TEST_REDIS_URL must be set");
+        let pool = PgPoolOptions::new()
+            .max_connections(16)
+            .connect(&database_url)
+            .await
+            .expect("connect quota test database");
+        sqlx::migrate!().run(&pool).await.expect("run migrations");
+        let state = build_test_state(pool.clone(), database_url, redis_url).await;
+        let marker = Uuid::new_v4().simple().to_string();
+        let mut cleanup = Vec::new();
+
+        let null_session = format!("quota-null-{marker}");
+        let null_ip: IpAddr = "198.51.100.11".parse().expect("parse fixture IP");
+        let null_date = reserve_anonymous_units(&state, &null_session, null_ip, 3)
+            .await
+            .expect("reserve NULL-rate batch quota");
+        let null_task = insert_anonymous_settlement_fixture(
+            &pool,
+            AnonymousSettlementFixture {
+                session_id: &null_session,
+                ip: null_ip,
+                date: null_date,
+                reserved_units: 3,
+                compression_rate: None,
+                total_files: 3,
+                completed_files: 3,
+            },
+        )
+        .await;
+        cleanup.push((null_task, null_session.clone(), null_ip, null_date));
+        assert_eq!(
+            settle_anonymous_task_reservation(&state, null_task)
+                .await
+                .expect("settle NULL-rate batch"),
+            Some(0)
+        );
+        assert_eq!(
+            anonymous_quota_counts(&state, &null_session, null_ip, null_date).await,
+            (3, 3)
+        );
+
+        let passthrough_session = format!("quota-passthrough-{marker}");
+        let passthrough_ip: IpAddr = "198.51.100.12".parse().expect("parse fixture IP");
+        let passthrough_date =
+            reserve_anonymous_units(&state, &passthrough_session, passthrough_ip, 3)
+                .await
+                .expect("reserve passthrough batch quota");
+        let passthrough_task = insert_anonymous_settlement_fixture(
+            &pool,
+            AnonymousSettlementFixture {
+                session_id: &passthrough_session,
+                ip: passthrough_ip,
+                date: passthrough_date,
+                reserved_units: 3,
+                compression_rate: Some(100),
+                total_files: 3,
+                completed_files: 3,
+            },
+        )
+        .await;
+        cleanup.push((
+            passthrough_task,
+            passthrough_session.clone(),
+            passthrough_ip,
+            passthrough_date,
+        ));
+        assert_eq!(
+            settle_anonymous_task_reservation(&state, passthrough_task)
+                .await
+                .expect("settle passthrough batch"),
+            Some(3)
+        );
+        assert_eq!(
+            anonymous_quota_counts(
+                &state,
+                &passthrough_session,
+                passthrough_ip,
+                passthrough_date,
+            )
+            .await,
+            (0, 0)
+        );
+
+        let partial_session = format!("quota-partial-{marker}");
+        let partial_ip: IpAddr = "198.51.100.13".parse().expect("parse fixture IP");
+        let partial_date = reserve_anonymous_units(&state, &partial_session, partial_ip, 3)
+            .await
+            .expect("reserve partial batch quota");
+        let partial_task = insert_anonymous_settlement_fixture(
+            &pool,
+            AnonymousSettlementFixture {
+                session_id: &partial_session,
+                ip: partial_ip,
+                date: partial_date,
+                reserved_units: 3,
+                compression_rate: None,
+                total_files: 3,
+                completed_files: 2,
+            },
+        )
+        .await;
+        cleanup.push((
+            partial_task,
+            partial_session.clone(),
+            partial_ip,
+            partial_date,
+        ));
+        assert_eq!(
+            settle_anonymous_task_reservation(&state, partial_task)
+                .await
+                .expect("settle partial batch"),
+            Some(1)
+        );
+        assert_eq!(
+            anonymous_quota_counts(&state, &partial_session, partial_ip, partial_date).await,
+            (2, 2)
+        );
+
+        let limit_session = format!("quota-limit-{marker}");
+        let limit_ip: IpAddr = "198.51.100.14".parse().expect("parse fixture IP");
+        let mut limit_date = None;
+        for batch in 0..2 {
+            let date = reserve_anonymous_units(&state, &limit_session, limit_ip, 5)
+                .await
+                .expect("reserve consecutive anonymous batch");
+            limit_date = Some(date);
+            let task_id = insert_anonymous_settlement_fixture(
+                &pool,
+                AnonymousSettlementFixture {
+                    session_id: &limit_session,
+                    ip: limit_ip,
+                    date,
+                    reserved_units: 5,
+                    compression_rate: None,
+                    total_files: 5,
+                    completed_files: 5,
+                },
+            )
+            .await;
+            cleanup.push((task_id, limit_session.clone(), limit_ip, date));
+            assert_eq!(
+                settle_anonymous_task_reservation(&state, task_id)
+                    .await
+                    .expect("settle consecutive anonymous batch"),
+                Some(0),
+                "batch {batch} unexpectedly refunded consumed units"
+            );
+        }
+        let limit_error = reserve_anonymous_units(&state, &limit_session, limit_ip, 1)
+            .await
+            .expect_err("daily anonymous quota was bypassed");
+        assert_eq!(limit_error.code, ErrorCode::QuotaExceeded);
+        assert_eq!(
+            anonymous_quota_counts(
+                &state,
+                &limit_session,
+                limit_ip,
+                limit_date.expect("limit quota date"),
+            )
+            .await,
+            (10, 10)
+        );
+
+        let mut redis = state.redis.clone();
+        for (task_id, session_id, ip, date) in cleanup {
+            sqlx::query("DELETE FROM tasks WHERE id = $1")
+                .bind(task_id)
+                .execute(&pool)
+                .await
+                .expect("delete quota settlement fixture");
+            let _: i64 = redis::cmd("DEL")
+                .arg(anonymous_session_key(&session_id, date))
+                .arg(anonymous_ip_key(ip, date))
+                .arg(format!("anon_quota_refund:{task_id}"))
+                .query_async(&mut redis)
+                .await
+                .expect("delete quota settlement Redis keys");
+        }
+    }
 }
diff --git a/src/worker/mod.rs b/src/worker/mod.rs
index ab0364d..d3c09e1 100644
--- a/src/worker/mod.rs
+++ b/src/worker/mod.rs
@@ -1086,11 +1086,14 @@ async fn process_task_file(
     } else {
         (original_size.saturating_sub(compressed_size) as f64) * 100.0 / (original_size as f64)
     };
-    let skip_charge = compression_rate == Some(100)
-        && format_in == format_out
-        && max_width.is_none()
-        && max_height.is_none();
-    let charge_units = !skip_charge && compressed_size < original_size;
+    let charge_units = quota::output_consumes_unit(
+        compression_rate,
+        format_in == format_out,
+        max_width.is_some() || max_height.is_some(),
+        false,
+        original_size,
+        compressed_size,
+    );
 
     let object_key = storage::result_attempt_key(
         ctx.retention_hours as i64,