Many allocation dimensions have a "long tail" problem where a significant number of elements account for a very small portion of total spend. This can impact materialization performance and query speed while delivering minimal analytical value.

You can use the ElementCutoff parameter to filter out these low-value elements from allocation dimensions. ElementCutoff sets a cumulative percentage threshold; elements that fall below this threshold are either excluded or grouped into a named bucket.

Supported allocation types

ElementCutoff is supported for the following allocation types:

How the threshold works

The threshold is based on cumulative allocation percentage, sorted in descending order by allocation value. Elements are included until the cumulative sum exceeds (100 - ThresholdPercent). A secondary sort by element value ensures deterministic results.

Elements that fall below the threshold can be handled in 2 ways:

• Excluded: Sub-threshold elements are excluded from the dimension (default behavior when no Name is specified).
• Grouped: Sub-threshold elements are aggregated into a named bucket (when Name is specified).

In both cases, the thresholded allocation values are renormalized so that non-excluded values sum to 1.0, ensuring cost allocation correctness.

Example

Given elements with the following original allocations and a threshold of 10%:

Exclude mode (no name specified)

Included elements (A, B, C) have an original sum of 0.90, so they are renormalized by dividing by 0.90:

Thresholded allocations sum to 1.0 (0.50 + 0.333 + 0.167).

Grouping mode (with name specified)

When grouping is enabled, the bucket receives the excluded allocation, so no renormalization is needed for included elements:

Thresholded allocations sum to 1.0 (0.45 + 0.30 + 0.15 + 0.10).

CostFormation syntax

Add an ElementCutoff block to your allocation dimension definition:

ElementCutoff:
  ThresholdPercent: 5      # Required: cumulative percentage threshold (0-100 exclusive)
  Name: 'Other'            # Optional: bucket name for grouped sub-threshold elements

Parameters

• ThresholdPercent (required): A number between 0 and 100 (exclusive). Determines the cumulative percentage of allocation below which elements are filtered out.
• Name (optional): A string that specifies the name of a grouping bucket. When provided, sub-threshold elements are aggregated into a single element with this name instead of being excluded. You can use any name that makes sense for your use case, for example, "Other", "Small Accounts", or "Long Tail".

Example: Exclude sub-threshold elements

The following example defines an allocation dimension that filters out elements in the bottom 5% of cumulative allocation:

RDSSplitCosts:
  Name: RDS Split Costs
  Hide: True
  Type: Allocation
  AllocateByRules:
    AllocationMethod: Proportional
    SpendToAllocate:
      Conditions:
        - And:
          - Source: Account
            Equals: 123456789012
          - Source: Service
            Equals: AWS RDS
    AcrossElements:
      Rules:
        - Type: GroupBy
          Source: SingleTenantProduct
  ElementCutoff:
    ThresholdPercent: 5

Example: Group sub-threshold elements

The following example groups sub-threshold elements into a bucket named "Small Accounts":

RDSSplitCosts:
  Name: RDS Split Costs
  Hide: True
  Type: Allocation
  AllocateByRules:
    AllocationMethod: Proportional
    SpendToAllocate:
      Conditions:
        - And:
          - Source: Account
            Equals: 123456789012
          - Source: Service
            Equals: AWS RDS
    AcrossElements:
      Rules:
        - Type: GroupBy
          Source: SingleTenantProduct
  ElementCutoff:
    ThresholdPercent: 10
    Name: 'Small Accounts'

Configuration priority

ElementCutoff can be configured at 2 levels. The following list describes the order of precedence, from highest to lowest:

1. CostFormation ElementCutoff: An explicit per-dimension configuration in your CostFormation definition file.
2. Organization default: A default threshold configured at the organization level by CloudZero. If you need help configuring an organization-level default, contact your FinOps Account Manager or Customer Success Representative.

If neither is configured, no threshold is applied and all elements are included (backward compatible default).

📘

To disable the cutoff for a specific dimension when an organization-level default is set, explicitly set ThresholdPercent: 0 in the dimension's ElementCutoff block.

Edge cases

• Single element: Always included regardless of threshold.
• Tied allocation values: A secondary sort by element value ensures deterministic results.
• Threshold of 0 or not configured: No elements are filtered (effectively disabled).
• Name collision with existing element: If the grouping bucket name matches an existing element, the sub-threshold values merge with that element.