The Britax Willow S Alpine expires 6 years after its date of manufacture, according to Britax.
What the maker says:
DO NOT use this infant car seat and base if it is older than six (6) years or has been in a moderate or severe crash.
Note: PDF p10. Counting basis from Britax FAQ.
Source: cdne1britaxus.azureedge.net, checked 2026-10-24.
Look up another model, or work out the date from a manufacture date