I am trying to calculate a Date based on two different columns in a SharePoint List: RANK column and PEBD column.

Essentially, I need to do the following:

IF RANK is E1, then the value of the column is PEBD + 6 YEARS - 1 DAY

OR

IF RANK is E3, then the value of the column is PEBD + 10 YEARS - 1 DAY

OR

IF RANK is E6, then the value of the column is PEBD + 22 YEARS - 1 DAY

I need to max out the 7 allowable nested statements and use the "IF FALSE" argument to return an 8th calculated date.

Here is what I came up with. The formula works with a single IF statement, but I haven't found a way to make nested statements work. TIA for any help. Code below:

 =IF([Rank]="E1",DATE(YEAR([PEBD])+6,MONTH([PEBD])+0,DAY([PEBD])-1)),IF([Rank]="E2",DATE(YEAR([PEBD])+6,MONTH([PEBD])+0,DAY([PEBD])-1)),IF([Rank]="E3",DATE(YEAR([PEBD])+10,MONTH([PEBD])+0,DAY([PEBD])-1)),IF([Rank]="E4",DATE(YEAR([PEBD])+12,MONTH([PEBD])+0,DAY([PEBD])-1)),IF([Rank]="E5",DATE(YEAR([PEBD])+20,MONTH([PEBD])+0,DAY([PEBD])-1)),IF([Rank]="E6",DATE(YEAR([PEBD])+22,MONTH([PEBD])+0,DAY([PEBD])-1)),IF([Rank]="E7",DATE(YEAR([PEBD])+24,MONTH([PEBD])+0,DAY([PEBD])-1)),DATE(YEAR([PEBD])+26,MONTH([PEBD])+0,DAY([PEBD])-1)))