Google Ads Seasonality Adjustments and Data Exclusions

This guide uses Google Ads Help: About seasonality adjustments, Create a seasonality adjustment, About data exclusions and Use data exclusions for conversion data outages, plus the Google Ads API pages linked below. Checked on 8 November 2026.

Why Smart Bidding needs these tools

Smart Bidding sets bids from your conversion history and from signals at the time of each auction. Our budgets and bid strategies guide explains the strategies themselves. That history is the weak point in two situations:

• A short event is coming that will change your conversion rate far more than usual, such as a 3-day sale. Smart Bidding learns from past results, and a one-off jump is not in that history.
• Your conversion data was wrong for a while: a tag fell off the site, the site was down, or an offline upload failed. Smart Bidding would otherwise read the gap as real low performance and bid down.

Seasonality adjustments cover the first case and data exclusions the second. Google calls both "an advanced tool". Neither changes your reports. They only change what Smart Bidding assumes.

The two tools side by side

One small inconsistency: the "Create" page lists Search, Standard Shopping and Display, without Demand Gen, while the "About" page includes Demand Gen. Check the scope list when you create the adjustment to see what your account offers.

Seasonality adjustments

Google describes a seasonality adjustment as a scheduled change to the conversion rate Smart Bidding expects, up or down, "which accounts for estimated changes due to an upcoming event." Its example: if you expect conversion rates to rise by 50% during a 3-day sale, you create an adjustment of up to +50% for those 3 days. Campaigns optimise bids during the event and "return to their pre-adjust performance after the event is finished", so you do not need a negative adjustment afterwards to cancel it out.

The main warning is in Google's own words: "Smart Bidding already manages seasonal events," so use adjustments only if you expect major changes to conversion rates. Regular peaks such as a holiday season are what Smart Bidding already learns from. Google's About Smart Bidding page lists seasonality as a signal for Shopping, where bids can follow seasonal performance trends during the year. Adjustments are for events your history does not predict, such as a one-off flash sale, a launch with heavy promotion elsewhere, or a short price cut.

Two practical points follow from how it works:

• Estimate the conversion rate change, not the traffic change. More visitors at the same conversion rate need no adjustment. The adjustment is about how likely each click is to convert.
• Keep it short. Google says adjustments are ideal for 1 to 7 days and may not work as well for more than 14 days at a time. For a lasting change, such as a permanent price drop, let Smart Bidding learn or change your targets instead.

Creating a seasonality adjustment

Google's steps for a single account:

1. Click the Tools icon, open the Budgets and bidding drop-down and click Adjustments.
2. Select Seasonal at the top and click the blue plus button.
3. Under "Adjustment type", select Conversion rate.
4. Enter a name, an optional description, and the event's start and end dates.
5. Under "Scope", choose campaign types (all or specific types), specific campaigns, or specific ad groups (App campaigns only). Device selection does not apply to App campaigns.
6. Under "Conversion rate adjustment", enter your estimated change, for example +50%.
7. Click Save, then Create seasonality adjustment.

If you pick specific campaigns, one event can hold up to 2,000 campaigns. For more, Google says to create another event or use the campaign type scope. Google also warns that adjustments "may change how your bid strategies perform", so check the dates and the percentage before you save. Start and end follow the account's time zone, which our ad scheduling guide covers.

Data exclusions

Data exclusions help "reduce the impact of conversion tracking issues in Smart Bidding." Google lists common causes as tagging issues, website outages and data import issues, for example a tag accidentally removed from the site. The key rules from Google's About page:

• They apply to clicks. You exclude the clicks that could have had the affected conversions attributed to them; their conversions are excluded with them.
• Only conversion or conversion value based Smart Bidding uses them. With an account-wide exclusion, conversions for Search, Display, Shopping and Performance Max campaigns are excluded.
• Reporting is unchanged. Only the data Smart Bidding uses is affected; the conversions still appear in your reports.
• No guarantee. Google says an exclusion "doesn't guarantee that your campaigns won't experience performance fluctuations."

Because exclusions work on click dates, the conversion delay matters. Google's example: if uploads failed from October 15 to October 18 and your conversion delay is 5 days, exclude October 10 to October 18, because clicks from October 10 onward could have converted in the broken window. Google's best practice is to exclude at least 90% of the clicks linked to the bad conversion data.

Creating a data exclusion

1. Go to Adjustments in the Tools menu and select the Exclusions tab.
2. Click the plus button and enter a name and description next to "Settings".
3. Enter the start and end date and time. Google says to choose a range that accounts for your typical conversion delay.
4. Next to "Scope", select individual campaigns or the entire account, and choose devices. Google's example is an issue that only affected mobile tracking.
5. Click Save, then Create data exclusion.

Apply it as soon as you find the problem. For a known future outage, such as scheduled site maintenance, Google recommends setting it in advance; future exclusions "typically take effect within a day". Google also says not to use exclusions "frequently or for extended periods", as this can hurt Smart Bidding performance. If outages keep happening, fix the tracking. Our conversion tracking guide and offline conversion import guide cover the setups that most often break.

After a data exclusion: targets, budgets and backfills

• Expect some movement. For past dates, Google says performance should begin to stabilise after a few days. If a week or more of clicks is affected, fluctuations may last 1 to 2 conversion cycles.
• Adjust targets and budgets. Google recommends adjusting Target CPA or Target ROAS for the performance you want, and keeping the budget close to historical spend for a few conversion cycles so you do not spend more than you are comfortable with.
• Bids may dip briefly. Google notes bids and spend can drop for a short time; lowering Target ROAS helps, but raise it back once the exclusion takes full effect to avoid overspending.
• Do not remove an exclusion once applied. Google says this "can cause more issues", even if you later fix the data.
• Be careful with backfills. Google generally advises against backfilling conversion data because it can directly affect Search and Shopping bidding. If an exclusion covers the period, you can backfill for reporting, but only at least 5 days after the exclusion was applied, and you should leave the exclusion in place.

Manager accounts and the API

From a manager account, a seasonality adjustment can cover all linked client accounts (all or specific campaign types), specific accounts, or specific campaigns, including client accounts in sub-manager accounts. It shows inside each client account. Google notes that client accounts linked later do not inherit it, and accounts that leave the manager keep showing the event. Data exclusions can be applied at manager or sub-account level, with times in the account's time zone.

The Google Ads API docs add details the Help pages leave out:

• Seasonality adjustments in the API take a conversion rate modifier between 0.1 and 10.0, used as a multiplier (1.0 means no change). Scope is campaigns (up to 2,000) or channel types, with optional devices.
• Data exclusions in the API are described as backward looking: the start is in the past, the end in the past or future. One exclusion can cover up to 2,000 campaigns, and each account can have at most 500 active exclusions. Through the API they must be created in a client account, not a manager account.

If you manage many accounts with code, our Google Ads scripts guide covers the scripting side.

When to use neither

• Normal seasonal peaks that recur every year: Google says Smart Bidding already manages them.
• A long change lasting weeks: an adjustment may not work well beyond 14 days. Change targets or budgets instead.
• Testing a new bid strategy or landing page: that is what Google Ads experiments are for.
• Low conversion volume in general: an exclusion fixes bad data, not too little data.

Neither tool replaces reliable tracking or a site that stays up during a sale.

Frequently asked questions

Do seasonality adjustments or data exclusions change my conversion reports?

No. Both only change what Smart Bidding uses. Google says excluded conversions can still be found in your reporting.

How long should a seasonality adjustment last?

Google says they are ideal for short events of 1 to 7 days and may not work as well for more than 14 days at a time.

Do I need a negative adjustment after a sale ends?

No. Google says campaigns return to their pre-adjust performance after the event, with no negative adjustment needed.

What dates should a data exclusion cover?

The clicks that could have converted during the problem. Start the range earlier by your conversion delay; Google's best practice is to exclude at least 90% of the affected clicks.

Can I remove a data exclusion once the tracking is fixed?

Google advises against it, because removing an applied exclusion can cause more issues. Backfill for reporting only after waiting at least 5 days, and leave the exclusion in place.

These tools only help if the data behind Smart Bidding is sound. See our budgets and bid strategies guide, our website development service and all our services, or email [email protected].