SQL Server 2019

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WITH CTE AS(
    SELECT V.Cod1,
           V.Cod2,
           Payed,
           CASE WHEN MIN(Cod2) OVER (PARTITION BY Cod1) = MAX(Cod2) OVER (PARTITION BY Cod1) THEN 0 ELSE 1 END AS C
    FROM (VALUES(1    ,'0001','000A',NULL),
                (2    ,'0001','000B','YES'),
                (3    ,'0001','000B','YES'),
                (4    ,'0001','000C',NULL),
                (5    ,'0001','000C','YELL'),
                (6    ,'0001','000D',NULL),
                (7    ,'0002','000A','YES'),
                (8    ,'0002','000C',NULL),
                (9    ,'0002','000C',NULL),
                (10   ,'0002','000C','YES'),
                (11   ,'0003','000C','YES'),
                (12   ,'0004','000C','YES'),
                (13   ,'0005','000A',NULL),
                (14   ,'0005','000A','YES'),
                (15   ,'0005','000A',NULL))V(Id,Cod1,Cod2,Payed))
SELECT Cod1,
       Cod2,
       COUNT(CASE Payed WHEN 'Yes' THEN 1 END) AS Payed,
       COUNT(CASE WHEN Payed IS NULL THEN 1 END) AS NotPayed
FROM CTE C
WHERE c = 1
GROUP BY Cod1,
         Cod2;

Cod1	Cod2	Payed	NotPayed
0001	000A	0	1
0001	000B	2	0
0001	000C	0	1
0001	000D	0	1
0002	000A	1	0
0002	000C	1	2

Warning: Null value is eliminated by an aggregate or other SET operation.