SharePoint Formula =IF(ISBLANK)
For each function (IF and ISBLANK) you need to have a pair of parentheses,
surrounding the argument(s) to that function.
ISBLANK takes one argument: the value that you want to check
for whether it is blank.
IF takes three arguments: the Boolean (true/false) value,
the "if true" value, and the "if false" value.
So your formula should be
=If(ISBLANK([Termination Date]),"",[Termination Date]+1826.21)
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