Look at the XIRR() function. Look in HELP for details.
XIRR() is part of Analysis Toolpak. If the function is not available;
ToolsOptionsAdd ins, check Analysis Toolpak

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Kind Regards,

Niek Otten

Microsoft MVP - Excel

"Brad" wrote in message
...
How can I build a function that will calculate an effective yield rate
given
that an individual can put in a lump sum at issue, have a different
premium
contribution between year 1 and renewal year?