Fifteen days back every month

Rivian built an AI system on Amazon Bedrock to handle purchase order accruals and cut more than 15 days of manual work out of every close cycle.

“We've not only eliminated weeks of manual work each month, but we've created a scalable foundation that will support our growth.”

The problem is genuinely hard

Custom tooling like stamping dies and injection molds takes one to two years to build, and the bill can land 18 months after the order. The cost still has to be recognized gradually.

They skipped more rigid rules

The obvious fix was writing tighter automation logic. Rivian didn't, because the real rules shifted with the size and type of each purchase.

Procedures as plain text

Rivian stored its actual accounting procedures as written instructions the AI reads directly. A finance manager edits a document and the AI picks up the change on its next run.

What the agent actually does

It watches for new purchase orders, checks its instructions, emails the right person when information is missing, calculates the amount owed, then drafts the accounting entry.

A human signs off, by design

Finance managers approve every entry before it posts. Auditors found the new trail easier to follow than the spreadsheets it replaced, and corrections get written back into the instructions.

“That human approval step isn't a workaround. It's intentional.”

Five weeks, then more

The proof of concept took five weeks before going live, and Rivian is already eyeing other finance tasks. It has company: 45% of CFOs report using AI in rules-based finance work.