Circular dependency error with Prior Month

[summer18]

I have a formula but getting "circular dependency error" that points to Prior Month budget but my formula is for Sales Actual.

Formula with error:

IF('Sales'[Department]="IT",0,'Sales'[YoY])

Here are the formulas related to my measure above:

YoY formula = (SUM(Actual)-[PY Actual]) / [PY Actual])

How can I fix the error?

[bcdobbs · Accepted solution]

I'm assuming that the formula you state is for a calculated column?

If so have a read of Avoiding circular dependency errors in DAX - SQLBI.

In the expression for the calculated column you want to wrap your [YoY] measure inside a calculate with an ALLEXCEPT to prevent it from adding everthing into the filter context.