# OPENINGBALANCEMONTH Function (DAX)

Evaluates the expression at the first date of the month in the current context.

## Syntax

```
OPENINGBALANCEMONTH(<expression>,<dates>[,<filter>])
```

## Parameters

Parameter |
Definition |

expression |
An expression that returns a scalar value. |

dates |
A column that contains dates. |

filter |
(optional) An expression that specifies a filter to apply to the current context. |

## Return Value

A scalar value that represents the expression evaluated at the first date of the month in the current context.

## Remarks

Note

To understand more about how context affects the results of formulas, see Context in DAX Formulas.

The dates argument can be any of the following:

A reference to a date/time column.

A table expression that returns a single column of date/time values.

A Boolean expression that defines a single-column table of date/time values.

Note

Constraints on Boolean expressions are described in the topic, CALCULATE Function (DAX).

Note

The filter expression has restrictions described in the topic, CALCULATE Function (DAX).

### Example

The following sample formula creates a measure that calculates the 'Month Start Inventory Value' of the product inventory.

To see how this works, create a PivotTable and add the fields, CalendarYear, MonthNumberOfYear and DayNumberOfMonth, to the **Row Labels** area of the PivotTable. Then add a measure, named Month Start Inventory Value, using the formula defined in the code section, to the **Values** area of the PivotTable.

### Code

```
=OPENINGBALANCEMONTH(SUMX(ProductInventory,ProductInventory[UnitCost]*ProductInventory[UnitsBalance]),DateTime[DateKey])
```

## See Also