The security period is the number of days Upwork holds a freelancer's earnings after an hourly invoice or a released milestone before the money becomes available to withdraw, during which a payment can be reversed or disputed.
Money on Upwork passes through three states. On an hourly contract the week's hours are invoiced when the weekly billing cycle closes and the client's review window runs; on a fixed-price contract a milestone is released by approval or automatically. In both cases the freelancer's share then appears as pending, and only when the security period has elapsed does it become available for withdrawal by one of the withdrawal methods on the account.
The hold exists so that Upwork has time to collect the client's payment, process a chargeback or a late dispute, and apply Hourly Payment Protection where it is owed. It is Upwork's buffer against paying out money it has not yet received. The length is set by Upwork, is stated in the Help Center, and differs between hourly and fixed-price work; it may change.
Two misreadings are common. Pending earnings are already earned and already counted in the profile's total: the security period delays access, not recognition. And the period is not a probation for new freelancers; it applies to every account, every week, for as long as the account earns. For an agency, the same hold applies to the agency's financial account before the owner can distribute funds to members.
How Upwork Insights uses it
This term describes Upwork's own rules or product rather than a figure the index measures; the pages that do carry live figures are the stats and rate pages.