diff --git a/tests/test_reports_balance.py b/tests/test_reports_balance.py
index 876c04bac72224fd53bc200ec0f8cae63790bcf7..d2866919669d796ddd00e084300370bc35752279 100644
--- a/tests/test_reports_balance.py
+++ b/tests/test_reports_balance.py
@@ -179,6 +179,84 @@ def test_eq(kwargs1, kwargs2, expected):
     actual = bal1 == bal2
     assert actual == expected
 
+@pytest.mark.parametrize('number,currency', {
+    (50, 'USD'),
+    (-50, 'USD'),
+    (50000, 'BRL'),
+    (-4000, 'BRL'),
+})
+def test_add_amount(number, currency):
+    start_amounts = testutil.balance_map(USD=500)
+    start_bal = core.Balance(start_amounts)
+    add_amount = testutil.Amount(number, currency)
+    actual = start_bal + add_amount
+    if currency == 'USD':
+        assert len(actual) == 1
+        assert actual['USD'] == testutil.Amount(500 + number)
+    else:
+        assert len(actual) == 2
+        assert actual['USD'] == testutil.Amount(500)
+        assert actual[currency] == add_amount
+    assert start_bal == start_amounts
+
+@pytest.mark.parametrize('number,currency', {
+    (50, 'USD'),
+    (-50, 'USD'),
+    (50000, 'BRL'),
+    (-4000, 'BRL'),
+})
+def test_iadd_amount(number, currency):
+    start_amounts = testutil.balance_map(USD=500)
+    balance = core.MutableBalance(start_amounts)
+    add_amount = testutil.Amount(number, currency)
+    balance += add_amount
+    if currency == 'USD':
+        assert len(balance) == 1
+        assert balance['USD'] == testutil.Amount(500 + number)
+    else:
+        assert len(balance) == 2
+        assert balance['USD'] == testutil.Amount(500)
+        assert balance[currency] == add_amount
+
+@pytest.mark.parametrize('balance_map_kwargs', [
+    {},
+    {'USD': 0},
+    {'EUR': 10},
+    {'JPY': 20, 'BRL': 30},
+    {'EUR': -15},
+    {'JPY': -25, 'BRL': -35},
+    {'JPY': 40, 'USD': 0, 'EUR': -50},
+])
+def test_add_balance(balance_map_kwargs):
+    start_numbers = {'USD': 500, 'BRL': 40000}
+    start_bal = core.Balance(testutil.balance_map(**start_numbers))
+    expect_numbers = start_numbers.copy()
+    for code, number in balance_map_kwargs.items():
+        expect_numbers[code] = expect_numbers.get(code, 0) + number
+    add_bal = core.Balance(testutil.balance_map(**balance_map_kwargs))
+    actual = start_bal + add_bal
+    expected = core.Balance(testutil.balance_map(**expect_numbers))
+    assert actual == expected
+
+@pytest.mark.parametrize('balance_map_kwargs', [
+    {},
+    {'USD': 0},
+    {'EUR': 10},
+    {'JPY': 20, 'BRL': 30},
+    {'EUR': -15},
+    {'JPY': -25, 'BRL': -35},
+    {'JPY': 40, 'USD': 0, 'EUR': -50},
+])
+def test_iadd_balance(balance_map_kwargs):
+    start_numbers = {'USD': 500, 'BRL': 40000}
+    balance = core.MutableBalance(testutil.balance_map(**start_numbers))
+    expect_numbers = start_numbers.copy()
+    for code, number in balance_map_kwargs.items():
+        expect_numbers[code] = expect_numbers.get(code, 0) + number
+    balance += core.Balance(testutil.balance_map(**balance_map_kwargs))
+    expected = core.Balance(testutil.balance_map(**expect_numbers))
+    assert balance == expected
+
 @pytest.mark.parametrize('balance_map_kwargs,expected', DEFAULT_STRINGS)
 def test_str(balance_map_kwargs, expected):
     amounts = testutil.balance_map(**balance_map_kwargs)