CPA, ERS, and ROAS is constraining the budget bid strategy

A budget bid strategy sets budgets, bids, and bid adjustments to efficiently spend the entire budget while maximizing the number of conversions or the amount of revenue achieved by the budget group. While spending, the budget bid strategy will achieve a range of different efficiencies (or returns on your investment),

The efficiency constraint specifies the maximum CPA or ERS, or minimum ROAS that a budget bid strategy can achieve while spending the budget. 

The constraint, if too low for CPA and ERS, or too high for ROAS, translates into being too narrow because it prevents the budget bid strategy from exceeding the efficiency rate to spend all of the budget. A too-narrow constraint forces a budget bid strategy to underspend to focus on meeting the efficiency constraint.

Without constraints, or with wider constraints, a budget bid strategy will spend as close as possible to your target budget. An efficiency constraint in a budget bid strategy is optional because it can prevent a budget bid strategy from spending the target amount.

If a budget bid strategy detects that it won't be able to reach your target spend within the constraints that you specify, a message warns you that the budget bid strategy will underspend unless the constraint is removed or adjusted. 

A budget bid strategy will always adhere to the efficiency constraint, even if it requires the bid strategy to set lower bids and spend less than the total budget.

Recommendation: Remove or adjust the minimum or maximum efficiency constraint to allow the budget bid strategy more room to make adjustments to spend the entire budget. 

Maximum CPA efficiency constraint

If you set a conversions goal in the budget plan, you set a maximum CPA or amount that you you would allow the budget bid strategy to reach while targeting your budget.

Minimum ROAS efficiency constraint

If you set a revenue goal in the budget plan, you set a maximum ERS or the minimum ROAS that you would allow the bid strategy to reach while targeting your budget. 

How to fix the issue

1. Navigate to the budget bid strategy.

   Steps for navigating to a budget bid strategy

   1. Navigate to an advertiser.

   2. In the left navigation panel, click Bid strategies.

      The Greek letter  Δ is appended to budget bid strategy names in the Bid strategy column.

      To view only budget bid strategies on the Bid strategy tab:

      1. Click the arrow ▼ next to View to display a list of predefined and custom reports.
      2. Click Budget bid strategy performance.
   3. Click the name of the budget bid strategy.

2. Navigate to the budget plan.

   1. Above the tabs, click View all plans.
      Search Ads 360 displays the Budget plans tab.

   2. Select the check box of the running plan.

   3. Click the Edit ▼ menu, and then click Edit details.
      The budget plan editor opens.
3. In the left navigation, click Budget automation settings.
4. Click + Constraints to expand the section.
5. Do the following as applicable:
   • For a CPA constraint, enter a higher amount.
   • For a ROAS constraint, enter a lower percent.
   • For an ERS constraint, enter a higher percent.
6. Optional. Change other settings in the plan.
7. In the left navigation, click Review plan details, and then click Save.