Can I enter a cost change I found out about late?

Yes. Save the new cost with its start set to the day the change really started: New prices from on Logistics, New fee from on Transaction fees, New cost from on Products. The days from that date on are worked out again with the new value. Everything before it keeps the value that was true then.

A typical case: your supplier raised a unit cost on 1 March, and the invoice told you in April. Save the new cost with New cost from 1 March. nouz ends the old cost on the last day of February. It works out every order from 1 March again, even a March you already reported on. January and February stay exactly as they were. The page tells you first, with a line like Orders from 1 Mar 2026 are priced again.

The same works for a carrier's new rate card and a payment provider's new fee. For an overhead cost that started earlier than you entered it, change its Start date. For a running overhead cost whose amount changed, Change applies from sets the day. One thing to know: a new version keeps every later version of that cost that you entered, and the page says so, like Your cost from 1 Dec 2026 stays. On Products, a cost that came from Shopify's sync after that date is replaced by yours, and the page names it before you save.

This is the one intended way a closed month changes, so do it on purpose. A month that moved should always have a reason, and a backdated cost carries its reason in its own start date.

If the old value was never right at all, a typo rather than a price change, correct that version instead. That rewrites it for all its days. To see what a cost change would do before you commit, try it in the Forecast's What if. It prices the months ahead without touching your history.