SQL Server 2019

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CREATE TABLE transfers(
   ID      INTEGER  NOT NULL PRIMARY KEY 
  ,cust_id INTEGER  NOT NULL
  ,final   INTEGER  NOT NULL
  ,date    DATE  NOT NULL
);
INSERT INTO transfers(ID,cust_id,final,date) VALUES (1,5,3000,'2020-09-22');
INSERT INTO transfers(ID,cust_id,final,date) VALUES (2,5,1500,'2020-09-25');
INSERT INTO transfers(ID,cust_id,final,date) VALUES (3,10,4000,'2020-09-28');
3 rows affected

CREATE TABLE trans_payments(
   ID      INTEGER  NOT NULL 
  ,cust_id INTEGER  NOT NULL
  ,value   INTEGER  NOT NULL
  ,date    DATE  NOT NULL
);
INSERT INTO trans_payments(ID,cust_id,value,date) VALUES (1,5,1000,'2020-09-22');
INSERT INTO trans_payments(ID,cust_id,value,date) VALUES (2,5,1500,'2020-09-23');
INSERT INTO trans_payments(ID,cust_id,value,date) VALUES (3,5,1000,'2020-10-01');
INSERT INTO trans_payments(ID,cust_id,value,date) VALUES (4,10,1000,'2020-09-28');
INSERT INTO trans_payments(ID,cust_id,value,date) VALUES (5,10,2000,'2020-01-01');
5 rows affected

select cust_id, final, value, date,
    sum(balance) over(partition by cust_id order by date, seq) balance
from (
        select cust_id, final, 0, final balance, date, 0 from transfers
        union all
        select cust_id, 0, value, -value, date, 1 from trans_payments
) t (cust_id, final, value, balance, date, seq)
order by cust_id, date, seq


cust_id
final
value
date
balance


5
3000
0
2020-09-22
3000

5
0
1000
2020-09-22
2000

5
0
1500
2020-09-23
500

5
1500
0
2020-09-25
2000

5
0
1000
2020-10-01
1000

10
0
2000
2020-01-01
-2000

10
4000
0
2020-09-28
2000

10
0
1000
2020-09-28
1000

cust_id	final	value	date	balance
5	3000	0	2020-09-22	3000
5	0	1000	2020-09-22	2000
5	0	1500	2020-09-23	500
5	1500	0	2020-09-25	2000
5	0	1000	2020-10-01	1000
10	0	2000	2020-01-01	-2000
10	4000	0	2020-09-28	2000
10	0	1000	2020-09-28	1000