An estimate gives a rough, non-binding price before work starts. A quote is a fixed price the client locks in by accepting it. An invoice is a formal request for payment after work is delivered. Most jobs flow estimate or quote, then work, then invoice. This article explains when to use each one, the legal differences, and the typical workflow for service businesses.
In most jurisdictions, yes — once the client accepts it. A quote with clear terms, an itemized scope, a price, and a validity period typically becomes a binding agreement.
Technically yes, but it's bad practice. The right approach is to issue a credit note and reissue a corrected invoice with a new number.
Industry standard is 14-30 days. Shorter periods create urgency and protect you from cost fluctuations on materials.
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