An open-ended quotation feels friendly in the moment and turns into a real problem the moment a client tries to accept it six months later, after your material costs went up or your schedule filled with other work.
What a validity date actually protects you from
Costs change. Suppliers raise prices, your own time becomes scarcer, currency rates shift for international clients. A clear expiry means an old quote can't be revived at a price that no longer makes sense for you.
It protects the client too, in a way
A validity window sets an honest expectation rather than an implicit promise that a price holds forever — which, if broken later, damages trust more than a clearly stated expiry date ever would.
What's a reasonable window?
15 to 30 days covers most standard proposals. Shorter (7 days) makes sense for anything tied to fast-moving material costs; longer (60-90 days) is reasonable for large projects with a naturally slower decision process on the client's side.
What to do when a quote expires unaccepted
Don't just silently honor the old price if a client comes back late — reissue a fresh quotation, adjusted if your costs have changed. This is a legitimate business practice, not something to feel awkward about.