Idempotent usage events: keys, dedupe windows and late arrivals
What a usage event's idempotency key should be made of, how long to keep it, and what to do with events that arrive after the billing period has closed.
Blog
Expert articles on EU billing, compliance and SaaS invoicing in the European market.
7 posts on Usage billing. Show all posts
October 2026 4 posts
Product catalogue versioning: plan versions, snapshots, grandfathering
Why a plan shouldn't just have a price: plan versions, sales and contract periods, pricing snapshots on the invoice line, and meter versions.
Seat-Based Billing: Proration, True-ups and Seat Removals in Numbers
20 seats added on 16 April, 10 removed in May, 30 more on an annual contract: three seat cases worked through, with the rules your contract should state.
SaaS Price Changes Without a Deploy: Versions, Grandfathering, Dates
From €99 to €119 per seat: what a new price means for monthly customers, annual contracts, grandfathered accounts and open quotes, and what breaks on the day.
August 2026 3 posts
Volume vs. Graduated Tiers: SaaS Tiered Pricing, Worked Through
One price table, two invoice totals: volume and graduated tiers worked through, with the boundary cliff, the counting scope and the rounding rule.
Overage Billing: Included Quotas, Excess Usage and Plan Changes
A plan with 5,000 included documents, worked through: what happens to the allowance on a mid-month upgrade and when the overage gets invoiced.
Evaluating usage-based billing software: a seven-test scorecard
A scorecard for usage-based billing: idempotency, late events, pricing models, traceability and EU tax, tested on your own data rather than vendor slides.