Can someone please help me regarding a formula which will enable me to
highlight upcoming birthdays on a spreadsheet.

I have no problem creating a formula to highlight, say, a date which falls
in the next 30 days. However, in this case the dates in question are my
friends' dates of birth so the years in such fields are not this year.

Can anyone help please?

If you store the birthdays as text, say, like this... Mar 8, July 23,
November 13, etc., then you can form the current years birthday in a column
using this formula...

=--(B2&", "&YEAR(NOW()))

You can then apply your current highlighter formula to that date.

Rick