Excel, generally, can have 7 levels of parens in a formula.
Usually, though, you don't need to use IF. If you're just looking up something from within the spreadsheet, LOOKUP is a useful formula. If you need to choose from a list, CHOOSE might work. VBA might have different limits, but it's a bit more involved and you probably don't need to use VBA.
Post the formula you want to write if you need more help.