diff --git a/cli/ConsistencyCheck.py b/cli/ConsistencyCheck.py
new file mode 100644
index 0000000..d9fceab
--- /dev/null
+++ b/cli/ConsistencyCheck.py
@@ -0,0 +1,127 @@
+from logging import error
+from db import dbGetMany
+from loguru import logger
+
+errorCnt = 0
+
+def perform(dbh, params):
+    global errorCnt
+    # checkTenant(dbh, params)
+    checkFlats(dbh, params)
+    checkParkings(dbh, params)
+    checkCommercialPremise(dbh, params)
+
+    if (errorCnt > 0):
+        logger.error(f"Total error count: {errorCnt}")
+
+def checkTenant(dbh, params):
+    global errorCnt
+    tenants = dbGetMany(dbh, { "statement": "SELECT * FROM tenant_t", "params": () })
+    for tenant in tenants:
+        outPre = f"Tenant: {tenant['firstname']} {tenant['lastname']}"
+        logger.info(outPre)
+
+        # check tenancies
+        tenancyCnt = 0
+        flatTenancyCnt = 0
+        tenancies = dbGetMany(dbh, { 
+                "statement": "SELECT * FROM tenancy_t WHERE tenant = %s AND startdate < now() AND (enddate > now() or enddate is null)", 
+                "params": (tenant['id'], )
+            }
+        )
+        for tenancy in tenancies:
+            tenancyCnt += 1
+            if (tenancy['flat']):
+                flatTenancyCnt += 1
+                logger.info(f"{outPre}: Flat tenancy: {tenancy['id']}, start: {tenancy['startdate']}, end: {tenancy['enddate']}")
+            if (tenancy['parking']):
+                logger.info(f"{outPre}: Garage tenancy: {tenancy['id']}, start: {tenancy['startdate']}, end: {tenancy['enddate']}")
+            if (tenancy['commercial_premise']):
+                logger.info(f"{outPre}: Commercial premise tenancy: {tenancy['id']}, start: {tenancy['startdate']}, end: {tenancy['enddate']}")
+
+        if (flatTenancyCnt == 0):
+            logger.warning(f"{outPre}: no flat tenancy")
+        if (flatTenancyCnt > 1):
+            logger.warning(f"{outPre}: more than one flat tenancy ({flatTenancyCnt})")
+        if (tenancyCnt == 0):
+            logger.error(f"{outPre}: no tenancy at all")
+            errorCnt += 1
+            noCurrentTenancies = dbGetMany(dbh, {
+                    "statement": "SELECT * FROM tenancy_t WHERE tenant = %s",
+                    "params": (tenant['id'], )
+                }
+            )
+            for noCurrentTenancy in noCurrentTenancies:
+                logger.error(f"{outPre}: but: flat {noCurrentTenancy['flat']}, parking: {noCurrentTenancy['parking']}, commercial premise: {noCurrentTenancy['commercial_premise']}, start: {noCurrentTenancy['startdate']}, end: {noCurrentTenancy['enddate']}")
+
+def _checkRentals(dbh, params, rentalType):
+    global errorCnt
+    table = f"{rentalType}_t"
+    rentals = dbGetMany(dbh, {
+            "statement": f"SELECT * FROM {table}",
+            "params": ()
+        }
+    )
+    for rental in rentals:
+        outPre = f"{rentalType}: {rental['description']}, premise: {rental['premise']}"
+        logger.info(outPre)
+
+        if (rentalType == 'flat'):
+            overheadMappingCnt = 0
+            overheadMappings = dbGetMany(dbh, {
+                    "statement": "SELECT * FROM overhead_advance_flat_mapping_t WHERE flat = %s",
+                    "params": (rental['id'], )
+                }
+            )
+            for overheadMapping in overheadMappings:
+                overheadMappingCnt += 1
+                logger.info(f"{outPre}: overhead mapping: {overheadMapping['id']}")
+            if (overheadMappingCnt == 0):
+                errorCnt += 1
+                logger.error(f"{outPre}: no overhead mapping available")
+            if (overheadMappingCnt > 1):
+                errorCnt += 1
+                logger.error(f"{outPre}: more than one overhead mapping available")
+
+        tenancyCnt = 0
+        tenancies = dbGetMany(dbh, {
+                "statement": f"SELECT * FROM tenancy_t WHERE {rentalType} = %s AND startdate < now() AND (enddate > now() or enddate is null)",
+                "params": (rental['id'], )
+            }
+        )
+        for tenancy in tenancies:
+            tenancyCnt += 1
+            logger.info(f"{outPre}: tenant: {tenancy['tenant']}, start: {tenancy['startdate']}, end: {tenancy['enddate']}")
+
+            feeMappingCnt = 0
+            feeMappings = dbGetMany(dbh, {
+                    "statement": "SELECT * FROM tenancy_fee_mapping_t where tenancy = %s",
+                    "params": (tenancy['id'], )
+                }
+            )
+            for feeMapping in feeMappings:
+                feeMappingCnt += 1
+                logger.info(f"{outPre}: fee mapping: {feeMapping['id']}")
+            if (feeMappingCnt == 0):
+                errorCnt += 1
+                logger.error(f"{outPre}: no fee mapping available")
+            if (feeMappingCnt > 1):
+                errorCnt += 1
+                logger.error(f"{outPre}: more than one fee mapping available")
+
+        if (tenancyCnt == 0):
+            errorCnt += 1
+            logger.error(f"{outPre}: vacant")
+        if (tenancyCnt > 1):
+            errorCnt += 1
+            logger.error(f"{outPre}: overbooked")
+
+
+def checkFlats(dbh, params):
+    _checkRentals(dbh, params, "flat")
+
+def checkParkings(dbh, params):
+    _checkRentals(dbh, params, "parking")
+
+def checkCommercialPremise(dbh, params):
+    _checkRentals(dbh, params, "commercial_premise")    
\ No newline at end of file
diff --git a/cli/hv2cli.py b/cli/hv2cli.py
index 6f4864a..3c598e0 100644
--- a/cli/hv2cli.py
+++ b/cli/hv2cli.py
@@ -6,7 +6,7 @@ import configparser
 import json
 import argparse
 import importlib
-
+import sys
 
 DB_USER = ""
 DB_PASS = ""
@@ -34,11 +34,19 @@ parser.add_argument('--params', '-p',
                     help='JSON string with parameter for the selected operation, default: {}',                    
                     required=False,
                     default="{}")
+parser.add_argument('--verbosity', '-v',
+                    help='Minimal log level for output: DEBUG, INFO, WARNING, ..., default: DEBUG',
+                    required=False,
+                    default="DEBUG")                    
 args = parser.parse_args()
 operation = args.operation
 params = json.loads(args.params)
+logLevel = args.verbosity
 
 
+logger.remove()
+logger.add(sys.stderr, colorize=True, level=logLevel)
+
 
 dbh = None
 try: