abyrvalg

select t2.birthday,
      date_add(
          date_add(
              makedate(b_year, 1),
              interval month(t2.birthday) - 1 month
            ),
          interval
            if(month(t2.birthday) = 2 and day(t2.birthday) = 29 and b_year % 4 <> 0,
               28,
              day(t2.birthday)
            )
            - 1 day
      ) nearest_birthday
from (
      select t.birthday,
             year(@now) +
             if(100 * month(t.birthday) + day(t.birthday) < 100 * month(@now) + day(@now),
               1,
               0
             ) b_year
      from t,
           (select @now := '2012-12-14') vars   -- <<== CURRENT DATE
    ) t2
having timestampdiff(day, @now, nearest_birthday) <= 85 -- <<== WINDOW
order by nearest_birthday
;

drop table if exists t;
create table t (
  birthday date not null
);

insert into t(birthday) values('1980-01-01');
insert into t(birthday) values('1980-01-15');
insert into t(birthday) values('1981-02-01');
insert into t(birthday) values('1981-02-15');
insert into t(birthday) values('2000-02-28');
insert into t(birthday) values('2000-02-29');
insert into t(birthday) values('1982-03-01');
insert into t(birthday) values('1982-03-15');
insert into t(birthday) values('1983-04-01');
insert into t(birthday) values('1983-04-15');
insert into t(birthday) values('1983-05-01');
insert into t(birthday) values('1983-05-15');
insert into t(birthday) values('1983-06-01');
insert into t(birthday) values('1983-06-15');
insert into t(birthday) values('1983-07-01');
insert into t(birthday) values('1983-07-15');
insert into t(birthday) values('1983-08-01');
insert into t(birthday) values('1983-08-15');
insert into t(birthday) values('1983-09-01');
insert into t(birthday) values('1983-09-15');
insert into t(birthday) values('1983-10-01');
insert into t(birthday) values('1983-10-15');
insert into t(birthday) values('1983-11-01');
insert into t(birthday) values('1983-11-15');
insert into t(birthday) values('1983-12-01');
insert into t(birthday) values('1983-12-15');