What is an acceptable IVT rate?
There is no official acceptable IVT rate, but many advertisers expect independently measured invalid traffic in the low single digits of impressions on protected campaigns, and treat sources that are consistently above that as suspect. Rates vary by channel, region and buying method, so compare each source against your own benchmark and against the same vendor's measurement.
The IVT rate you see depends on who measures it, whether it includes SIVT or only GIVT, and whether pre-bid filtering already removed the worst traffic. A campaign with pre-bid blocking can show a very low post-bid rate simply because suspicious impressions were never bought. Open-exchange inventory, incentivized placements and some app and CTV segments tend to run higher than direct deals with premium publishers.
Use IVT rates to rank and prune supply rather than as a pass/fail grade. Put rate thresholds in contracts alongside refunds and clawbacks terms, and watch trends: a sudden jump in one app or domain often signals a new scheme or a new reseller in the path.