diff --git a/test/functional/tests/io_class/test_io_class_occupancy_resize.py b/test/functional/tests/io_class/test_io_class_occupancy_resize.py
new file mode 100644
index 0000000..01039c4
--- /dev/null
+++ b/test/functional/tests/io_class/test_io_class_occupancy_resize.py
@@ -0,0 +1,133 @@
+#
+# Copyright(c) 2020 Intel Corporation
+# SPDX-License-Identifier: BSD-3-Clause-Clear
+#
+
+from recordclass import recordclass
+
+import pytest
+
+from .io_class_common import *
+from api.cas.cache_config import CacheMode, CacheLineSize
+from api.cas.ioclass_config import IoClass
+from storage_devices.disk import DiskType, DiskTypeSet, DiskTypeLowerThan
+from test_tools import fs_utils
+from test_tools.disk_utils import Filesystem
+from test_utils.os_utils import sync, Udev
+
+
+@pytest.mark.require_disk("cache", DiskTypeSet([DiskType.optane, DiskType.nand]))
+@pytest.mark.require_disk("core", DiskTypeLowerThan("cache"))
+@pytest.mark.parametrizex("cache_line_size", CacheLineSize)
+@pytest.mark.parametrize("new_occupancy", [0, 20, 70, 100])
+def test_ioclass_resize(cache_line_size, new_occupancy):
+    """
+        title: Resize ioclass
+        description: |
+          Add ioclass, fill it with data, change it's size and check if new
+          limit is respected
+        pass_criteria:
+          - Occupancy threshold is respected
+    """
+    with TestRun.step("Prepare CAS device"):
+        cache, core = prepare(cache_mode=CacheMode.WT, cache_line_size=cache_line_size)
+        cache_size = cache.get_statistics().config_stats.cache_size
+
+    with TestRun.step("Disable udev"):
+        Udev.disable()
+
+    with TestRun.step(f"Prepare filesystem and mount {core.system_path} at {mountpoint}"):
+        filesystem = Filesystem.xfs
+        core.create_filesystem(filesystem)
+        core.mount(mountpoint)
+        sync()
+
+    with TestRun.step("Prepare test dirs"):
+        IoclassConfig = recordclass("IoclassConfig", "id eviction_prio max_occupancy dir_path")
+        io_class = IoclassConfig(1, 3, 0.50, f"{mountpoint}/A")
+
+    fs_utils.create_directory(io_class.dir_path, parents=True)
+
+    with TestRun.step("Remove old ioclass config"):
+        ioclass_config.remove_ioclass_config()
+        ioclass_config.create_ioclass_config(False)
+
+    with TestRun.step("Add default ioclasses"):
+        ioclass_config.add_ioclass(*str(IoClass.default(allocation="0.00")).split(","))
+
+    with TestRun.step("Add directory for ioclass"):
+        ioclass_config.add_ioclass(
+            io_class.id,
+            f"directory:{io_class.dir_path}&done",
+            io_class.eviction_prio,
+            f"{io_class.max_occupancy:0.2f}",
+        )
+
+        casadm.load_io_classes(cache_id=cache.cache_id, file=ioclass_config_path)
+
+    with TestRun.step("Reset cache stats"):
+        cache.purge_cache()
+        cache.reset_counters()
+
+    with TestRun.step("Check initial occupancy"):
+        occupancy = get_io_class_occupancy(cache, io_class.id)
+        if occupancy.get_value() != 0:
+            TestRun.LOGGER.error(
+                f"Incorrect inital occupancy for ioclass id: {io_class.id}."
+                f" Expected 0, got: {occupancy}"
+            )
+
+    with TestRun.step(f"Perform IO with size equal to cache size"):
+        run_io_dir(f"{io_class.dir_path}/tmp_file", int((cache_size) / Unit.Blocks4096))
+
+    with TestRun.step("Check if the ioclass did not exceed specified occupancy"):
+        actuall_occupancy = get_io_class_occupancy(cache, io_class.id)
+
+        occupancy_limit = (
+            (io_class.max_occupancy * cache_size)
+            .align_up(Unit.Blocks4096.get_value())
+            .set_unit(Unit.Blocks4096)
+        )
+
+        if actuall_occupancy > occupancy_limit:
+            TestRun.LOGGER.error(
+                f"Occupancy for ioclass id exceeded: {io_class.id}. "
+                f"Limit: {occupancy_limit}, actuall: {actuall_occupancy}"
+            )
+
+    with TestRun.step(
+        f"Resize ioclass from {io_class.max_occupancy*100}% to {new_occupancy}%" " cache occupancy"
+    ):
+        io_class.max_occupancy = new_occupancy / 100
+        ioclass_config.remove_ioclass_config()
+        ioclass_config.create_ioclass_config(False)
+
+        ioclass_config.add_ioclass(*str(IoClass.default(allocation="0.00")).split(","))
+
+        ioclass_config.add_ioclass(
+            io_class.id,
+            f"directory:{io_class.dir_path}&done",
+            io_class.eviction_prio,
+            f"{io_class.max_occupancy:0.2f}",
+        )
+
+        casadm.load_io_classes(cache_id=cache.cache_id, file=ioclass_config_path)
+
+    with TestRun.step(f"Perform IO with size equal to cache size"):
+        run_io_dir(f"{io_class.dir_path}/tmp_file", int((cache_size) / Unit.Blocks4096))
+
+    with TestRun.step("Check if the ioclass did not exceed specified occupancy"):
+        actuall_occupancy = get_io_class_occupancy(cache, io_class.id)
+
+        occupancy_limit = (
+            (io_class.max_occupancy * cache_size)
+            .align_up(Unit.Blocks4096.get_value())
+            .set_unit(Unit.Blocks4096)
+        )
+
+        # Divergency may be casued be rounding max occupancy
+        if actuall_occupancy > occupancy_limit + Size(100, Unit.Blocks4096):
+            TestRun.LOGGER.error(
+                f"Occupancy for ioclass id exceeded: {io_class.id}. "
+                f"Limit: {occupancy_limit}, actuall: {actuall_occupancy}"
+            )