diff --git a/app/celery/tasks.py b/app/celery/tasks.py
index dc69427a5..92af2bdac 100644
--- a/app/celery/tasks.py
+++ b/app/celery/tasks.py
@@ -11,6 +11,7 @@ from notifications_utils.template import (
     SMSMessageTemplate,
     WithSubjectTemplate,
 )
+from notifications_utils.timezones import convert_utc_to_bst
 from requests import (
     HTTPError,
     request,
@@ -72,7 +73,6 @@ from app.models import (
 )
 from app.notifications.process_notifications import persist_notification
 from app.service.utils import service_allowed_to_send_to
-from app.utils import convert_utc_to_bst
 
 
 @notify_celery.task(name="process-job")
diff --git a/app/clients/performance_platform/performance_platform_client.py b/app/clients/performance_platform/performance_platform_client.py
index d04b22659..66cecb4c0 100644
--- a/app/clients/performance_platform/performance_platform_client.py
+++ b/app/clients/performance_platform/performance_platform_client.py
@@ -4,7 +4,7 @@ import json
 from flask import current_app
 import requests
 
-from app.utils import convert_utc_to_bst
+from notifications_utils.timezones import convert_utc_to_bst
 
 
 class PerformancePlatformClient:
diff --git a/app/config.py b/app/config.py
index b5bcbb42b..1ba7d6edc 100644
--- a/app/config.py
+++ b/app/config.py
@@ -1,4 +1,4 @@
-from datetime import timedelta, time
+from datetime import timedelta
 import os
 import json
 
@@ -318,8 +318,6 @@ class Config(object):
     DOCUMENT_DOWNLOAD_API_HOST = os.environ.get('DOCUMENT_DOWNLOAD_API_HOST', 'http://localhost:7000')
     DOCUMENT_DOWNLOAD_API_KEY = os.environ.get('DOCUMENT_DOWNLOAD_API_KEY', 'auth-token')
 
-    LETTER_PROCESSING_DEADLINE = time(17, 30)
-
     MMG_URL = "https://api.mmg.co.uk/json/api.php"
     AWS_REGION = 'eu-west-1'
 
diff --git a/app/dao/date_util.py b/app/dao/date_util.py
index 1e93e845f..f9533a826 100644
--- a/app/dao/date_util.py
+++ b/app/dao/date_util.py
@@ -1,9 +1,8 @@
 from datetime import datetime, timedelta
 
+from notifications_utils.timezones import convert_bst_to_utc
 import pytz
 
-from app.utils import convert_bst_to_utc
-
 
 def get_months_for_financial_year(year):
     return [
diff --git a/app/dao/fact_billing_dao.py b/app/dao/fact_billing_dao.py
index e3f7f221b..bdc2011a6 100644
--- a/app/dao/fact_billing_dao.py
+++ b/app/dao/fact_billing_dao.py
@@ -1,6 +1,7 @@
 from datetime import datetime, timedelta, time
 
 from flask import current_app
+from notifications_utils.timezones import convert_bst_to_utc, convert_utc_to_bst
 from sqlalchemy.dialects.postgresql import insert
 from sqlalchemy import func, case, desc, Date, Integer
 
@@ -20,7 +21,6 @@ from app.models import (
     EMAIL_TYPE,
     NOTIFICATION_STATUS_TYPES_BILLABLE_FOR_LETTERS
 )
-from app.utils import convert_utc_to_bst, convert_bst_to_utc
 
 
 def fetch_billing_totals_for_year(service_id, year):
diff --git a/app/dao/fact_notification_status_dao.py b/app/dao/fact_notification_status_dao.py
index 566d5f40e..f80f175d8 100644
--- a/app/dao/fact_notification_status_dao.py
+++ b/app/dao/fact_notification_status_dao.py
@@ -1,6 +1,7 @@
 from datetime import datetime, timedelta, time
 
 from flask import current_app
+from notifications_utils.timezones import convert_bst_to_utc
 from sqlalchemy import func
 from sqlalchemy.dialects.postgresql import insert
 from sqlalchemy.sql.expression import literal
@@ -8,7 +9,7 @@ from sqlalchemy.types import DateTime, Integer
 
 from app import db
 from app.models import Notification, NotificationHistory, FactNotificationStatus, KEY_TYPE_TEST
-from app.utils import convert_bst_to_utc, get_london_midnight_in_utc, midnight_n_days_ago
+from app.utils import get_london_midnight_in_utc, midnight_n_days_ago
 
 
 def fetch_notification_status_for_day(process_day, service_id=None):
diff --git a/app/dao/notifications_dao.py b/app/dao/notifications_dao.py
index f170c2410..564ab6acf 100644
--- a/app/dao/notifications_dao.py
+++ b/app/dao/notifications_dao.py
@@ -20,6 +20,7 @@ from sqlalchemy.orm import joinedload
 from sqlalchemy.sql.expression import case
 from sqlalchemy.sql import functions
 from notifications_utils.international_billing_rates import INTERNATIONAL_BILLING_RATES
+from notifications_utils.timezones import convert_utc_to_bst
 
 from app import db, create_uuid
 from app.aws.s3 import remove_s3_object, get_s3_bucket_objects
@@ -48,7 +49,7 @@ from app.models import (
 )
 
 from app.dao.dao_utils import transactional
-from app.utils import convert_utc_to_bst, get_london_midnight_in_utc
+from app.utils import get_london_midnight_in_utc
 
 
 @statsd(namespace="dao")
diff --git a/app/letters/utils.py b/app/letters/utils.py
index fc84b50ac..03cd573f9 100644
--- a/app/letters/utils.py
+++ b/app/letters/utils.py
@@ -4,10 +4,11 @@ from enum import Enum
 import boto3
 from flask import current_app
 
+from notifications_utils.letter_timings import LETTER_PROCESSING_DEADLINE
 from notifications_utils.s3 import s3upload
+from notifications_utils.timezones import convert_utc_to_bst
 
 from app.models import KEY_TYPE_TEST, SECOND_CLASS, RESOLVE_POSTAGE_FOR_FILE_NAME, NOTIFICATION_VALIDATION_FAILED
-from app.utils import convert_utc_to_bst
 
 
 class ScanErrorType(Enum):
@@ -26,7 +27,7 @@ def get_folder_name(_now, is_test_or_scan_letter=False):
         folder_name = ''
     else:
         print_datetime = convert_utc_to_bst(_now)
-        if print_datetime.time() > current_app.config.get('LETTER_PROCESSING_DEADLINE'):
+        if print_datetime.time() > LETTER_PROCESSING_DEADLINE:
             print_datetime += timedelta(days=1)
         folder_name = '{}/'.format(print_datetime.date())
     return folder_name
diff --git a/app/models.py b/app/models.py
index 8cb2e6ede..e2d86679a 100644
--- a/app/models.py
+++ b/app/models.py
@@ -26,6 +26,7 @@ from notifications_utils.template import (
     SMSMessageTemplate,
     LetterPrintTemplate,
 )
+from notifications_utils.timezones import convert_bst_to_utc, convert_utc_to_bst
 
 from app.encryption import (
     hashpw,
@@ -38,7 +39,6 @@ from app import (
 )
 
 from app.history_meta import Versioned
-from app.utils import convert_utc_to_bst, convert_bst_to_utc
 
 SMS_TYPE = 'sms'
 EMAIL_TYPE = 'email'
diff --git a/app/notifications/process_notifications.py b/app/notifications/process_notifications.py
index 46b78941d..6483ac766 100644
--- a/app/notifications/process_notifications.py
+++ b/app/notifications/process_notifications.py
@@ -9,6 +9,7 @@ from notifications_utils.recipients import (
     validate_and_format_phone_number,
     format_email_address
 )
+from notifications_utils.timezones import convert_bst_to_utc, convert_utc_to_bst
 
 from app import redis_store
 from app.celery import provider_tasks
@@ -34,8 +35,6 @@ from app.v2.errors import BadRequestError
 from app.utils import (
     cache_key_for_service_template_counter,
     cache_key_for_service_template_usage_per_day,
-    convert_bst_to_utc,
-    convert_utc_to_bst,
     get_template_instance,
 )
 
diff --git a/app/notifications/receive_notifications.py b/app/notifications/receive_notifications.py
index b73730ece..848c7d239 100644
--- a/app/notifications/receive_notifications.py
+++ b/app/notifications/receive_notifications.py
@@ -3,6 +3,7 @@ from urllib.parse import unquote
 import iso8601
 from flask import jsonify, Blueprint, current_app, request, abort
 from notifications_utils.recipients import try_validate_and_format_phone_number
+from notifications_utils.timezones import convert_bst_to_utc
 
 from app import statsd_client
 from app.celery import tasks
@@ -11,7 +12,6 @@ from app.dao.services_dao import dao_fetch_service_by_inbound_number
 from app.dao.inbound_sms_dao import dao_create_inbound_sms
 from app.models import InboundSms, INBOUND_SMS_TYPE, SMS_TYPE
 from app.errors import register_errors
-from app.utils import convert_bst_to_utc
 
 receive_notifications_blueprint = Blueprint('receive_notifications', __name__)
 register_errors(receive_notifications_blueprint)
diff --git a/app/service/statistics.py b/app/service/statistics.py
index 10bff90b3..3d22b20d6 100644
--- a/app/service/statistics.py
+++ b/app/service/statistics.py
@@ -1,8 +1,9 @@
 from collections import defaultdict
 from datetime import datetime
 
+from notifications_utils.timezones import convert_utc_to_bst
+
 from app.models import NOTIFICATION_STATUS_TYPES, TEMPLATE_TYPES
-from app.utils import convert_utc_to_bst
 from app.dao.date_util import get_months_for_financial_year
 
 
diff --git a/app/utils.py b/app/utils.py
index 9dacd616c..b00a53bda 100644
--- a/app/utils.py
+++ b/app/utils.py
@@ -4,6 +4,7 @@ import pytz
 from flask import url_for
 from sqlalchemy import func
 from notifications_utils.template import SMSMessageTemplate, WithSubjectTemplate
+from notifications_utils.timezones import convert_utc_to_bst
 
 local_timezone = pytz.timezone("Europe/London")
 
@@ -51,14 +52,6 @@ def get_midnight_for_day_before(date):
     return get_london_midnight_in_utc(day_before)
 
 
-def convert_utc_to_bst(utc_dt):
-    return pytz.utc.localize(utc_dt).astimezone(local_timezone).replace(tzinfo=None)
-
-
-def convert_bst_to_utc(date):
-    return local_timezone.localize(date).astimezone(pytz.UTC).replace(tzinfo=None)
-
-
 def get_london_month_from_utc_column(column):
     """
      Where queries need to count notifications by month it needs to be
diff --git a/requirements-app.txt b/requirements-app.txt
index e9e2e4674..8e1812f49 100644
--- a/requirements-app.txt
+++ b/requirements-app.txt
@@ -29,6 +29,6 @@ awscli-cwlogs>=1.4,<1.5
 # Putting upgrade on hold due to v1.0.0 using sha512 instead of sha1 by default
 itsdangerous==0.24  # pyup: <1.0.0
 
-git+https://github.com/alphagov/notifications-utils.git@30.5.6#egg=notifications-utils==30.5.6
+git+https://github.com/alphagov/notifications-utils.git@30.7.0#egg=notifications-utils==30.7.0
 
 git+https://github.com/alphagov/boto.git@2.43.0-patch3#egg=boto==2.43.0-patch3
diff --git a/requirements.txt b/requirements.txt
index d80c5f3e3..a21b7c1ff 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -31,21 +31,21 @@ awscli-cwlogs>=1.4,<1.5
 # Putting upgrade on hold due to v1.0.0 using sha512 instead of sha1 by default
 itsdangerous==0.24  # pyup: <1.0.0
 
-git+https://github.com/alphagov/notifications-utils.git@30.5.6#egg=notifications-utils==30.5.6
+git+https://github.com/alphagov/notifications-utils.git@30.7.0#egg=notifications-utils==30.7.0
 
 git+https://github.com/alphagov/boto.git@2.43.0-patch3#egg=boto==2.43.0-patch3
 
 ## The following requirements were added by pip freeze:
-alembic==1.0.2
+alembic==1.0.3
 amqp==1.4.9
 anyjson==0.3.3
 attrs==18.2.0
-awscli==1.16.53
+awscli==1.16.61
 bcrypt==3.1.4
 billiard==3.3.0.23
 bleach==2.1.3
 boto3==1.6.16
-botocore==1.12.43
+botocore==1.12.51
 certifi==2018.10.15
 chardet==3.0.4
 Click==7.0
@@ -68,7 +68,7 @@ phonenumbers==8.9.4
 pyasn1==0.4.4
 pycparser==2.19
 PyPDF2==1.26.0
-pyrsistent==0.14.5
+pyrsistent==0.14.7
 python-dateutil==2.7.5
 python-editor==1.0.3
 python-json-logger==0.1.8
diff --git a/requirements_for_test.txt b/requirements_for_test.txt
index d286b3400..824f9482d 100644
--- a/requirements_for_test.txt
+++ b/requirements_for_test.txt
@@ -1,6 +1,6 @@
 -r requirements.txt
 flake8==3.6.0
-pytest==3.10.0
+pytest==3.10.1
 moto==1.3.7
 pytest-env==0.6.2
 pytest-mock==1.10.0
diff --git a/tests/app/dao/test_ft_billing_dao.py b/tests/app/dao/test_ft_billing_dao.py
index 213fed7a9..f36e02180 100644
--- a/tests/app/dao/test_ft_billing_dao.py
+++ b/tests/app/dao/test_ft_billing_dao.py
@@ -6,6 +6,8 @@ from freezegun import freeze_time
 
 import pytest
 
+from notifications_utils.timezones import convert_utc_to_bst
+
 from app import db
 from app.dao.fact_billing_dao import (
     delete_billing_data_for_service_for_day,
@@ -20,7 +22,6 @@ from app.models import (
     Notification,
     NOTIFICATION_STATUS_TYPES,
 )
-from app.utils import convert_utc_to_bst
 from tests.app.db import (
     create_ft_billing,
     create_service,
diff --git a/tests/app/test_utils.py b/tests/app/test_utils.py
index d6488946d..8f105b588 100644
--- a/tests/app/test_utils.py
+++ b/tests/app/test_utils.py
@@ -6,8 +6,6 @@ from freezegun import freeze_time
 from app.utils import (
     get_london_midnight_in_utc,
     get_midnight_for_day_before,
-    convert_utc_to_bst,
-    convert_bst_to_utc,
     midnight_n_days_ago,
     last_n_days
 )
@@ -31,26 +29,6 @@ def test_get_midnight_for_day_before_returns_expected_date(date, expected_date):
     assert get_midnight_for_day_before(date) == expected_date
 
 
-@pytest.mark.parametrize('date, expected_date', [
-    (datetime(2017, 3, 26, 23, 0), datetime(2017, 3, 27, 0, 0)),    # 2017 BST switchover
-    (datetime(2017, 3, 20, 23, 0), datetime(2017, 3, 20, 23, 0)),
-    (datetime(2017, 3, 28, 10, 0), datetime(2017, 3, 28, 11, 0)),
-    (datetime(2017, 10, 28, 1, 0), datetime(2017, 10, 28, 2, 0)),
-    (datetime(2017, 10, 29, 1, 0), datetime(2017, 10, 29, 1, 0)),
-    (datetime(2017, 5, 12, 14), datetime(2017, 5, 12, 15, 0))
-])
-def test_get_utc_in_bst_returns_expected_date(date, expected_date):
-    ret_date = convert_utc_to_bst(date)
-    assert ret_date == expected_date
-
-
-def test_convert_bst_to_utc():
-    bst = "2017-05-12 13:15"
-    bst_datetime = datetime.strptime(bst, "%Y-%m-%d %H:%M")
-    utc = convert_bst_to_utc(bst_datetime)
-    assert utc == datetime(2017, 5, 12, 12, 15)
-
-
 @pytest.mark.parametrize('current_time, arg, expected_datetime', [
     # winter
     ('2018-01-10 23:59', 1, datetime(2018, 1, 9, 0, 0)),