What is the syntax for ISOMITTED in Excel?

The syntax for ISOMITTED is: =ISOMITTED(argument)

What are common errors with ISOMITTED?

Only works inside LAMBDA functions

What is ISOMITTED used for?

ISOMITTED checks if an optional LAMBDA parameter was provided. It enables default values: =LAMBDA(x, [multiplier], IF(ISOMITTED(multiplier), x*2, x*multiplier)). If multiplier is omitted, it defaults to 2.

What is the difference between ISOMITTED and ISBLANK?

ISOMITTED checks if a LAMBDA parameter wasn't passed at all. ISBLANK checks if a value is empty. A parameter can be passed as blank (ISBLANK=TRUE, ISOMITTED=FALSE) or not passed (ISOMITTED=TRUE).

How do I create a LAMBDA with optional parameters?

Put optional params in brackets: =LAMBDA(required, [optional], formula). Use ISOMITTED to provide defaults: =LAMBDA(value, [decimals], ROUND(value, IF(ISOMITTED(decimals), 2, decimals))). This rounds to 2 decimals by default.

Information

ISOMITTED Function in Excel

Checks whether a value in a LAMBDA is missing and returns TRUE or FALSE.

Syntax

=ISOMITTED(argument)

Arguments

argument (required): LAMBDA parameter to check

Examples

=LAMBDA(x, IF(ISOMITTED(x), "default", x)) - Check for missing argument - Result: Value or default

Defensive formulas with ISOMITTED

Use IS* functions inside IF to branch on blank, error, text, or number cells.
Prefer [IFERROR](/functions/iferror/) when you only need a fallback display value.
Error hub: [Fix formula errors](/guides/fix-excel-formula-errors/).

Common errors

Only works inside LAMBDA functions

Use cases

Optional parameters
Default values
LAMBDA validation

Frequently asked questions

What is ISOMITTED used for? ISOMITTED checks if an optional LAMBDA parameter was provided. It enables default values: =LAMBDA(x, [multiplier], IF(ISOMITTED(multiplier), x*2, x*multiplier)). If multiplier is omitted, it defaults to 2.
What is the difference between ISOMITTED and ISBLANK? ISOMITTED checks if a LAMBDA parameter wasn't passed at all. ISBLANK checks if a value is empty. A parameter can be passed as blank (ISBLANK=TRUE, ISOMITTED=FALSE) or not passed (ISOMITTED=TRUE).
How do I create a LAMBDA with optional parameters? Put optional params in brackets: =LAMBDA(required, [optional], formula). Use ISOMITTED to provide defaults: =LAMBDA(value, [decimals], ROUND(value, IF(ISOMITTED(decimals), 2, decimals))). This rounds to 2 decimals by default.

Editorial review

Reviewed by Excel.Directory Editorial Team. Updated May 2026.