Does a partner buyout require its own separate valuation, or can we just use an old one?

It's generally worth getting a current valuation rather than relying on an old one, since a business's value can change significantly over time due to revenue, contracts, assets, or market conditions — an outdated figure may no longer reflect what the business, or the departing partner's share of it, is actually worth today. If your shareholders' agreement specifies a valuation method or formula, that governs how the number should be calculated now, even if a valuation was done previously for some other purpose, such as financing, a prior dispute, or an earlier ownership change.

Using a stale number without updating it risks the buyout price being unfair to one side or the other, and unfair pricing is a common source of later disputes or claims that the buyout wasn't handled properly. A fresh, properly documented valuation, even if it largely confirms an earlier figure, gives both partners confidence that the price reflects the business as it stands today.