That depends on how detailed you need to be. Costs are derived from
resource rates. For each resource, there is a rate table in the Resource
Information screen (double click the ID number to the left of the resource
name). Enter the effective date for the increase. In the rate column you
can enter either the new rate to be used after that date or you can enter
something like "+5%" and it will calculate it for you.
Personally I wouldn't bother with that much detail - these are cost
estimates, not an accounting system, and unless inflation in your area is
leaping out of control, the uncertainty in the work estimates that are the
basis for costs will far exceeed the variances you get when you take into
account the inflation rate. If I estimate a task is going to cost $1000 +/-
20% (which is by no means an unusual level of uncertainty, that means the
range I expect it to cost is somewhere between $800 and $1200. If I factor
in inflation at 3% per year and the task is one year away, the $1000 becomes
$1030 and my new expected range becomes about $825-$1235, hardly a
signifigant difference from the unadjusted estimate. If the task is far
enough into the future out that inflation would account for a signifigant
amount, the uncertainty in the work and duration estimates that far away
also increases, probably being as much as +/- 50% or more for tasks 10-15
years down the road and would still overshadow the inflation variance.
If I really HAD to factor in inflation, I think I'd just export the
timephased annual totals over to Excel and do the calculation there.
