Dim cnnLocal As New ADODB.Connection
    Dim rstCurr  As New ADODB.Recordset
    Dim dblVal As Double    
   
    Set cnnLocal = CurrentProject.Connection
        rstCurr.Open "SELECT * FROM qryCalcContractObjectSum", cnnLocal, adOpenStatic, adLockReadOnly
    dblVal = rstCurr("sum_price")  ' <--- тут вылезает Type Mismatch 
    rstCurr.Close
    
    Set cnnLocal = Nothing

SELECT SUM(...) AS sum_price
...
далее куча джойнов
....

DECALARE @res NUMERIC(9,4)

SELECT @res = SUM(...)
...куча джойнов...

SELECT @res AS sum_price