The Digital Services Tax (DST) is a UK tax on large search engines, social media platforms and online marketplaces, charged on the revenue they earn from UK users. It has applied since April 2020. It is paid by the platforms, not by advertisers, but some of them pass the cost on as a separate fee on ads shown to people in the UK.
How the Digital Services Tax works
The tax only applies to groups above high revenue thresholds, so a UK business buying ads will never owe DST itself. What reaches you is the platform’s decision to recover it. Google, for example, adds a DST fee to the cost of ads served to users in the UK, and other ad platforms and marketplaces have made similar choices. Whether a fee applies, and how it is calculated, is set by each platform and can change.
Three details catch people out:
- It follows the viewer, not the advertiser. The fee is usually based on where the ad was shown. A UK business advertising only to Ireland may see no UK DST line; an overseas business advertising to London will.
- It sits outside your campaign figures. The fee typically appears on the invoice or in the billing summary as its own line, not in the Cost column of your campaigns. Your daily budget is not reduced by it, but your bank account is.
- VAT is a separate question. How VAT is applied to ad spend and to the fee depends on which entity bills you and your VAT status. The entry on VAT on digital advertising covers that part.
I am deliberately not quoting a rate here. Check the fee line and the platform’s current billing help page rather than relying on a figure you read somewhere, because both the tax and the way platforms pass it on have been reviewed more than once. At the time of writing (October 2026), the tax remains in place; GOV.UK carries the current position.
Why it matters for a UK business
If you judge campaigns on the numbers in the ad platform, every figure is slightly flattering. Your cost per acquisition is understated and your return on ad spend is overstated by the amount of the fee. For a business working on thin margins, such as an online shop selling at a 20% gross margin, a target ROAS set without the fee can mean campaigns that look profitable in the dashboard but lose money in the accounts.
It also affects budget conversations. If a client or finance director approves £5,000 a month for Google Ads and the invoice comes to more than that before VAT, someone will ask why. Knowing the fee exists and showing it as its own line in forecasts avoids that conversation.
Common mistakes
- Setting targets from in-platform cost alone and never reconciling against invoices.
- Assuming the fee is a mistake or a hidden charge and raising a billing dispute.
- Copying a fee rate from an old article instead of reading the current invoice.
- Forgetting the fee when comparing channels, so one platform looks cheaper than it is.
- Treating the fee as part of VAT and reclaiming it as input tax without checking with an accountant.
How to act on it
Download last month’s invoice or billing statement for each ad account and find the DST line, if there is one. Work out what it adds as a proportion of spend, and use that to correct your reporting:
- Add the fee to cost in your own reports, so CPA and ROAS reflect what you actually pay.
- Adjust targets accordingly. If your break-even ROAS on spend was 4.0, recalculate it on spend plus fees.
- Show the fee separately in budgets and forecasts, so approvals cover the real total.
- Ask your accountant how the fee and any VAT should be recorded in your books.
Your payments profile in Google Ads holds the invoices and statements you need. Reconciling platform figures with real costs is a standard part of the PPC management reporting I provide.