Need help with syntax - adding a filter when calculating a sum please

RichardJ You may find this helpful - https://community.powerbi.com/t5/Community-Blog/To-bleep-With-Time-Intelligence/ba-p/1260000

Also, see if my Time Intelligence the Hard Way provides a different way of accomplishing what you are going for.

https://community.powerbi.com/t5/Quick-Measures-Gallery/Time-Intelligence-quot-The-Hard-Way-quot-TITHW/m-p/434008

Turned out the solution was pretty simple in the end.

Total Costs Program1 = 

CALCULATE (
   SUM(DataTable[Cost])+0,
   FILTER ( ALL ( DataTable ), DataTable[Program]= "Program1" && DataTable[Mode] = "Internal" ),   
   PREVIOUSYEAR('Calendar'[Date])
)