Simple question - accounting for leap years in formulas calculating dates

Try

=IF($B4=1029,DATE(YEAR($A4)-1,MONTH(A4),DAY(A4)),IF($B4=1030,DATE(YEAR($A4)-2,MONTH(A4),DAY(A4)),IF($B4=1031,DATE(YEAR($A4)-5,MONTH(A4),DAY(A4)))))

If the anniversary is on the SAME month & day.