SQL Server 2019

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create table amounts
(
    userId int,
    year int,
    month int,
    amount int
)
insert into amounts values 
(132,2019, 9,836),
(132,2019,10,702),
(132,2019,11,161),
(132,2019,12,955),
(132,2020, 1,969),
(132,2020, 2,977),
(132,2020, 3,986),
(132,2020, 4,639),
(132,2020, 5,411),
(132,2020, 6,302),
(132,2020, 7,929),
(132,2020, 8,884),
(132,2020, 9,644),
(132,2020,10,640),
(132,2020,11,121),
(132,2020,12,980),
(1447,2020,11,356),
(1447,2020,12,351);
18 rows affected

select userId, cycle, sum(amount) as amount
from
(
    select *, cycle = (row_number() over (partition by userId order by year, month) - 1) /12 + 1
    from   amounts
) t
group by userId, cycle
order by userId, cycle


userId
cycle
amount


132
1
8751

132
2
2385

1447
1
707