"naffyb" wrote:
Excel easily calculates IRRs where cash initially is invested/spent
and then followed by a series of incomes. However, I have
situation where I need to calculate IRR where the cash invested
is spread over a number of years, rather than being invested as
a lump sum up front. Incomes start before the cash is fully
invested and continue thereafter.
How do you calculate IRR in this instance?

The IRR() function should work for your case, as well. It is not limited to
one negative cash flow followed by only positive cash flows.

What makes you think it is? Post an example of your usage.

PS: If the cash flows come at irregular intervals -- not simply annually or
monthly or weekly, for example -- then use XIRR(). Also, be sure to follow
the sign convention consistently, typically negative numbers for outflows and
positive numbers for inflows.