Agency overspent a client's ad budget: what now

If your agency overspent a client's ad budget, work out the cause before you write to anyone. Google documents a monthly ceiling of 30.4 times the average daily budget for most campaigns. Set each daily budget at the monthly figure divided by 30.4 and that ceiling equals your agreed budget. Who pays the difference is decided by your agreement, not by Google.

This page covers Google Ads. Meta's daily budget rules differ and are not covered here. To see the next overspend coming, read how to catch an overspend before your client does.

How much can Google Ads spend against your budget?

Google Ads Help states both limits:

Your daily spending limit (two times your average daily budget for most campaigns) on any particular day.

Your monthly spending limit (30.4 times your average daily budget for most campaigns) in any particular month.

Source: Google Ads Help, answer 6385083, checked 3 September 2026. Note "for most campaigns" before you quote these multipliers to a client.

daily budget     = monthly budget / 30.4
most in one day  = daily budget x 2
most in a month  = daily budget x 30.4

A client on €3,000 a month gets a daily budget of €98.68. Any single day can reach €197.37, and the documented monthly limit is exactly €3,000.00. So a €180 day is not an overspend. With the budget unchanged all month, the limit still holds the month to €3,000. Why Google Ads spent more than the daily budget covers the daily side.

Step 1: work out what actually happened

Run three checks, in this order:

1. Add up the daily budgets. Total the average daily budgets of every campaign on the account and multiply by 30.4. A result above the agreed monthly budget means the budget was set too high.
2. Compare each campaign with its ceiling. Set its spend for the month against its daily budget times 30.4.
3. Find the day spend jumped. Look in the account's change history for a budget edit, a new campaign or a resumed one on that date.

If a daily budget changed during the month, check 2 does not apply cleanly. List each change and its date before you conclude anything.

A daily budget set as the monthly figure divided by 28

Somebody divides by four weeks, or by February. €3,000 / 28 is €107.14 a day.

107.14 x 30.4     = 3,257.06   Google's documented monthly limit
3,257.06 - 3,000  =   257.06   up to 8.6% over the agreement

No single day looks wrong, so nobody notices until the month closes. Dividing by 30 is the same mistake, smaller: €100.00 a day and a limit of €3,040.00.

A budget typed with an extra zero

The daily budget is rounded to €99 and typed as €990. One day can now reach €1,980, and the monthly limit becomes €30,096. Three days of full delivery come to €2,970, almost the whole month. The trace is a step change: spend jumps on the day of the edit and stays up.

A campaign left running

A promotion was agreed at €40 a day for ten days, €400 in total. Nobody paused it. Over a 30-day month it spends €1,200 at its daily budget, against a documented limit of €1,216. That is up to €816 the client never approved. Check campaign by campaign, because underdelivery elsewhere can hide it in the account total.

Spend above Google's documented limit

A campaign that spent more than 30.4 times its daily budget in a month, with no budget change, went past the limit Google documents. Raise it with Google, with the figures, and tell your client you have.

Step 2: who pays depends on your agreement

Google's limits say what a campaign may spend, not who carries an overage. Your agreement decides that. This is not legal advice. For a disputed amount, ask a lawyer in your jurisdiction.

Check the agreement for:

• Who approves spend. Does the client sign off a budget each month? Can you change budgets without asking?
• Cap or target. "Up to €3,000 a month" is a cap, so every euro above it is outside the agreement. "About €3,000 a month" is a target, and some variance may sit inside it.
• How overages are handled. Look for a tolerance and for who pays above it.
• Monthly or daily terms. If the agreement names a daily figure, Google's limit lets one day reach twice it.
• Fees on spend. If your fee is a percentage of spend, decide whether it applies to the overspend.

If the agreement is silent, you are negotiating. You can credit the overage on your next invoice, which is the clean answer when the budget was a cap and the setup was yours. You can offset it against next month's spend, if the client accepts the extra spend. Or you can waive your fee on it.

Step 3: what to say to the client

Write before the invoice arrives. Take the figure from the platform's own billing, not from a dashboard, including Adswave's. If the daily budget was set too high, do not write that Google overspent. Your client can check that sentence against Google's help page.

Subject: [Client] Google Ads, [month]: €251.20 over budget

Hi [name],

Google Ads spend for [client] in [month] was €3,251.20.
The agreed budget was €3,000.00, so we spent €251.20 (8.4%) more.

The cause was ours. We set the daily budget at €107.14, the
monthly budget divided by 28. It should have been divided by
30.4, which gives €98.68.

We corrected it on [date]. [Remedy: we will credit €251.20 on
this month's invoice.]

What changes: every daily budget is now the monthly budget
divided by 30.4, checked by a second person. We also get an
alert when spend runs more than 5% ahead of the budget's pace.

Happy to go through the numbers on a call this week.

[Your name]

If the cause was one heavy day inside Google's limits, keep it shorter. Give the day's spend, quote Google's two-times rule and show where the month stands.

How to stop it happening again

Set daily budgets as the monthly figure divided by 30.4. That makes Google's documented monthly limit equal the agreed figure. The Google Ads daily budget calculator does the division and shows both limits.

Alert on pacing variance, not on totals. Variance is how far actual spend sits from what the budget calls for over the same days.

expected    = monthly budget / 30.4 x days in the window
variance %  = (actual - expected) / expected x 100

Over seven days the €3,000 client should spend €690.79. At €107.14 a day it spends €749.98, which is 8.6 per cent ahead. A 5 per cent overspend alert catches the divide-by-28 mistake in the first week. A 10 per cent alert never would, because this error runs at a steady 8.6 per cent.

Correct mid-month. An error found before month end may still be recoverable.

budget left       = monthly budget - spend to the end of yesterday
days left         = days in month - today's date + 1
new daily budget  = budget left / days left

Say the divide-by-28 budget is found on the morning of the 11th of a 30-day month. Ten days of full delivery at €107.14 is €1,071.40. That leaves €1,928.60 for 20 days, so the new daily budget is €96.43. Any one day can still reach €192.86, so check again a few days later. The mid-month budget adjustment calculator runs this for one client. If spend already meets the monthly budget, no daily figure fixes the month. Pause, or agree the overspend with the client.

What Adswave does about it

Adswave compares Google Ads and Meta spend with each client's monthly budget. It is read-only, so you make every fix in the platform yourself.

The Budget Pacing view shows expected against actual spend per client over rolling windows of 2, 14, 30, 90, 180 and 365 days ending today, split by Google and Meta. Variance is green at 2 per cent or less, amber up to 5 per cent and red above it, over and under alike. You enter budgets per linked ad account in the Client dialog.

Pacing alerts compare actual spend over the last 1, 7, 14 or 30 complete days with the monthly budget / 30.4 times those days. Thresholds are 5, 10, 15, 20, 25, 30, 45 or 50 per cent, and an "up" rule watches for overspend. On a client rule, each linked ad account is checked against its own budget. Rules are evaluated hourly and fire at most once per target in 24 hours. Emails go to owners and admins with alert emails on, while members see alerts in the app. Pacing and alerts are on every plan, with 20 alert rules on Basic, 50 on Standard and 200 on Pro.

The limits, stated plainly:

• Alert windows end yesterday, so a mistake made this morning reaches an alert only after the day completes.
• The pacing view shows no projected month-end spend.
• In the pacing view, today counts as a full day while its spend is partial. Every window leans toward underspend until the day completes.
• Expected spend uses 30.4 days in every month. A client spending evenly through a 28-day February shows about +8.6 per cent, which is red.

Questions people ask

Who is responsible when an agency overspends a client's budget?

Your agreement with the client decides, not any platform rule. Check who approves spend, whether the budget is a cap or a target, and how overages are handled. If your setup caused it, expect the client to see it as yours to fix.

Should an agency refund overspend?

It depends on the agreement and the cause. A cap exceeded through your own setup error points to a credit. Spend inside an agreed tolerance on a target budget may need no refund. In between, offer options and let the client choose.

How do I tell a client we overspent?

In writing, before the invoice arrives. Give the exact amount from the platform's billing and the cause in one sentence. Then give the fix with its date and what changes so it does not happen again.

Can Google Ads spend more than my monthly budget?

Google documents a monthly limit of 30.4 times the average daily budget for most campaigns. With the daily budget at your monthly figure divided by 30.4, that limit equals your monthly figure. A higher daily budget raises it.

Adswave checks budget pacing for every client across Google Ads and Meta, read-only, with alerts on every plan. Start a 7-day free trial, no card required.

Google budget limits quoted from Google Ads Help, answer 6385083, checked 3 September 2026. Nothing on this page is legal advice.