Audit days are the amount of auditor time allocated to your certification audit. They are the main driver of what a certification body charges.
They are not arbitrary
Audit time is governed by IAF MD 5, a mandatory document that accredited certification bodies work to. Table QMS 1 sets a baseline number of days against the effective number of personnel within your certification scope, for the initial certification audit — Stage 1 and Stage 2 combined.
This means you can check a quote. Ask the certification body for the personnel count they used, the baseline days from the table, and the adjustments they applied. A reputable one will show you without friction.
Adjustments
The standard permits reductions of up to 30% of the table figure, for factors including no design responsibility, maturity of the management system, prior certification to another standard, and high levels of automation.
Increases are not capped in the same way. Multiple buildings, several languages in use, highly regulated sectors such as food, pharmaceuticals, aerospace or nuclear, and unusually complex or varied processes all push time upward.
Beyond year one
Budget for the full three-year cycle, not the certificate. Surveillance audits in years two and three each run at roughly a third of the initial audit time. Recertification at year three is roughly two-thirds. A first-year figure alone materially understates the real cost.
What the table excludes
MD 5 audit time does not include travel or report writing. Those still appear on the invoice.