diff --git a/sql/v01/10.create.sql b/sql/v01/10.create.sql
index 1a4b5af..1cf1636 100644
--- a/sql/v01/10.create.sql
+++ b/sql/v01/10.create.sql
@@ -646,6 +646,7 @@ CREATE TABLE payment_variant (
     CONSTRAINT pk_payment PRIMARY KEY (year, avnr)
 ) STRICT;
 
+-- all values in the table are stored with season-precision!
 CREATE TABLE payment_delivery_part (
     year     INTEGER NOT NULL,
     did      INTEGER NOT NULL,
@@ -710,16 +711,15 @@ BEGIN
     WHERE (year, avnr, mgnr) = (OLD.year, OLD.avnr, (SELECT mgnr FROM delivery WHERE (year, did) = (OLD.year, OLD.did)));
 END;
 
+-- all values in the table are stored with season-precision!
 CREATE TABLE payment_member (
     year   INTEGER NOT NULL,
     avnr   INTEGER NOT NULL,
     mgnr   INTEGER NOT NULL,
 
     amount INTEGER NOT NULL,
-    tgnr   INTEGER DEFAULT NULL,
 
     CONSTRAINT pk_payment_member PRIMARY KEY (year, avnr, mgnr),
-    CONSTRAINT sk_payment_member_tgnr UNIQUE (year, tgnr),
     CONSTRAINT fk_payment_member_payment_variant FOREIGN KEY (year, avnr) REFERENCES payment_variant (year, avnr)
         ON UPDATE CASCADE
         ON DELETE CASCADE,
@@ -727,3 +727,33 @@ CREATE TABLE payment_member (
         ON UPDATE CASCADE
         ON DELETE CASCADE
 ) STRICT;
+
+-- all values in the table are stored with precision 2!
+CREATE TABLE credit (
+    year            INTEGER NOT NULL,
+    tgnr            INTEGER NOT NULL,
+
+    mgnr            INTEGER NOT NULL,
+    avnr            INTEGER NOT NULL,
+
+    net_amount      INTEGER NOT NULL,
+    prev_net_amount INTEGER,
+    vat             REAL    NOT NULL,
+    vat_amount      INTEGER NOT NULL GENERATED ALWAYS AS (ROUND((net_amount - COALESCE(prev_net_amount, 0)) * vat)) VIRTUAL,
+    gross_amount    INTEGER NOT NULL GENERATED ALWAYS AS (net_amount - COALESCE(prev_net_amount, 0) + vat_amount) VIRTUAL,
+    modifiers       INTEGER,
+    prev_modifiers  INTEGER,
+    amount          INTEGER NOT NULL GENERATED ALWAYS AS (gross_amount + COALESCE(modifiers, 0) - COALESCE(prev_modifiers, 0)) STORED,
+
+    ctime         INTEGER NOT NULL DEFAULT (UNIXEPOCH()),
+    mtime         INTEGER NOT NULL DEFAULT (UNIXEPOCH()),
+
+    CONSTRAINT pk_credit PRIMARY KEY (year, tgnr),
+    CONSTRAINT sk_credit_payment_member UNIQUE (year, avnr, mgnr),
+    CONSTRAINT fk_credit_member FOREIGN KEY (mgnr) REFERENCES member (mgnr)
+        ON UPDATE CASCADE
+        ON DELETE RESTRICT,
+    CONSTRAINT fk_credit_payment_member FOREIGN KEY (year, avnr, mgnr) REFERENCES payment_member (year, avnr, mgnr)
+        ON UPDATE CASCADE
+        ON DELETE RESTRICT
+);
diff --git a/sql/v01/11.timestamp-trigger.sql b/sql/v01/11.timestamp-trigger.sql
index 7337a2a..fb2b951 100644
--- a/sql/v01/11.timestamp-trigger.sql
+++ b/sql/v01/11.timestamp-trigger.sql
@@ -283,4 +283,34 @@ CREATE TRIGGER t_payment_member_d_mtime_payment_variant
     AFTER DELETE ON payment_member FOR EACH ROW
 BEGIN
     UPDATE payment_variant SET mtime = UNIXEPOCH() WHERE (year, avnr) = (OLD.year, OLD.avnr);
-END;
\ No newline at end of file
+END;
+
+----------------------------------------------------------------
+
+CREATE TRIGGER t_credit_i_ctime
+    AFTER INSERT ON credit FOR EACH ROW
+    WHEN NEW.ctime != UNIXEPOCH()
+BEGIN
+    UPDATE credit SET ctime = UNIXEPOCH() WHERE (year, tgnr) = (NEW.year, NEW.tgnr);
+END;
+
+CREATE TRIGGER t_credit_u_ctime
+    BEFORE UPDATE ON credit FOR EACH ROW
+    WHEN OLD.ctime != NEW.ctime
+BEGIN
+    SELECT RAISE(ABORT, 'It is not allowed to change ctime');
+END;
+
+CREATE TRIGGER t_credit_i_mtime
+    AFTER INSERT ON credit FOR EACH ROW
+    WHEN NEW.mtime != UNIXEPOCH()
+BEGIN
+    UPDATE credit SET mtime = UNIXEPOCH() WHERE (year, tgnr) = (NEW.year, NEW.tgnr);
+END;
+
+CREATE TRIGGER t_credit_u_mtime
+    AFTER UPDATE ON credit FOR EACH ROW
+    WHEN NEW.mtime != UNIXEPOCH()
+BEGIN
+    UPDATE credit SET mtime = UNIXEPOCH() WHERE (year, tgnr) = (NEW.year, NEW.tgnr);
+END;