Chargeback and Showback
Attributing cloud cost to the teams that generate it — either informationally (showback) or by moving it onto their budget (chargeback).
Showback reports each team's spend without moving money. Low friction, and usually enough: teams that can see their costs generally act on them, and it avoids arguments about allocation methodology.
Chargeback actually transfers the cost to the team's budget. Stronger incentive, and it creates real overhead — disputes about shared costs, gaming, and the risk that teams optimise their own line at the expense of the whole.
Both depend on allocation coverage, which is the hard part. Tags must be applied at provisioning and enforced by policy, or a meaningful fraction of spend is unattributable and the report loses credibility. Shared costs — the platform, the observability stack, the network — need an agreed apportionment rule decided once rather than argued monthly.
Start with showback and unit costs. Move to chargeback only if showback demonstrably fails, because the incentive it adds is rarely worth the process it creates.