What is cost aggregation?

Why it needs a name

Adding up what you spent sounds like a solved problem. It is not, because every platform reports spend in its own currency, on its own billing cycle, with its own definition of what counts, under its own campaign taxonomy, and revises the numbers afterwards.

Every efficiency metric a marketing organisation produces has spend in the denominator. If that denominator is assembled inconsistently, every one of them is wrong — and wrong quietly, in a way that looks like performance.

What has to be reconciled

• Currency, at a consistent rate and date rather than whatever each platform used.
• Fee treatment, so gross and net are not mixed within one report.
• Time periods, since platform days and business days differ by timezone.
• Campaign taxonomy, mapped to one structure so the same campaign is one row.
• Revisions, with a settlement rule for how long spend stays provisional.

Where it silently breaks

The most common failure is fee inconsistency: one platform's reported spend includes its fee and another's does not, so a channel appears materially more efficient than a competitor purely because of accounting. Nothing errors and nobody notices until a budget has moved.

The second is timezone drift. A platform reporting in UTC against a business reporting locally produces a persistent offset that shows up as a weekly pattern in efficiency metrics and gets explained as consumer behaviour.

The third is unmapped campaigns, which fall into an 'other' bucket that grows quietly until a meaningful share of spend is unattributed to any channel.