Need help converting Tableau calculation to DAX formula

[Ashley1]

I know this is a very simple formula but I am not able to incorporate it in Power BI. Please help

IF ZN(SUM([TotalSales])) - LOOKUP(ZN(SUM([TotalSales])), -1)>0 THEN 'Surplus'
ELSE 'Deficit'
END

Thank you in advance!

[Kaviraj11 · Accepted solution]

IF (
ISBLANK(SUM([TotalSales])) - CALCULATE(SUM([TotalSales]), PREVIOUSMONTH('Table'[Date])) > 0,
"Surplus",
"Deficit"
)