# The Excel COUPDAYBS Function

Related Functions:
COUPDAYS
COUPDAYSNC

## Basic Description

The Excel COUPDAYBS function calculates the number of days from the beginning of a coupon's period to the settlement date.

The syntax of the function is :

COUPDAYBS( settlement, maturity, frequency, [basis] )

Where the arguments are as follows:

settlement-The settlement date of the security
maturity-The maturity date of the security
frequency-

The number of coupon payments per year. Must be either:

 1 - Annually 2 - Semi-Annually 4 - Quarterly
[basis]-An optional argument which defines the day count basis to be used in the calculation.
Possible values of basis and their meanings are :
BasisDay Count Basis
0 (or omitted)US (NASD) 30/360
1actual/actual
2actual/360
3actual/365
4European 30/360
The financial day count basis rules are explained in more detail on the Wikipedia Day Count Convention page

Note that the settlement and maturity dates should be input as either:

• References to cells containing dates
or
• Dates returned from formulas

- If you attempt to input these dates as text, there is a chance that Excel may misinterpret this due to different date systems, or date interpretation settings.

Warning: Although you can input the dates as serial numbers, this is not recommended as the serial numbers may vary across different computer systems.

## Excel Coupdaybs Function Example

Cell A3 of the spreadsheet below contains an example of the Excel Coupdaybs function, used to calculate the number of days from the beginning of a coupon's period to the settlement date. The security has the settlement date 01-Jan-2011, the maturity date 25-Oct-2012, and 4 payments per year. The US (NASD) 30/360 day count basis is used.

The format of the function is shown in the spreadsheet on the left and the result is shown in the spreadsheet on the right.

Formulas:
A
101-Jan-2011
225-Oct-2012
3=COUPDAYBS( A1, A2, 4 )
Results:
A
101-Jan-2011
225-Oct-2012
376

Note that, in the above example :

• As recommended by Microsoft, the date arguments have been input as references to cells containing dates
• As the [basis] argument has been omitted, the function uses the default value 0 (denoting the US (NADS) 30/360 day count basis)

More details and examples of the Excel Coupdaybs function are provided on the Microsoft Office website.

## Coupdaybs Function Errors

If you get an error from the Excel Coupdaybs Function, this is most likely to be one of the following:

Common Errors
 #NUM! - Occurs if either:the supplied settlement date is ≥ maturity datethe supplied frequency argument is a number that is not equal to 1, 2 or 4the supplied [basis] argument is a number that is not equal to 0, 1, 2, 3 or 4 #VALUE! - Occurs if either:the supplied settlement or the supplied maturity date is not a valid Excel datethe supplied frequency or the supplied [basis] argument is non-numeric #NAME? - Occurs when Analysis ToolPak add-in is not enabled in your Excel.You will need to enable the add-in if you want to use the Excel Coupdaybs function.