Quotes, estimates and proformas — three documents, three promises

A quote (quotation) is a fixed price for a defined scope: if the client accepts it as written, that is the price, and changes are handled as variations. An estimate is a professional approximation: the final price follows the actual work and materials, and the document should say so in words — "estimate" alone in the title is weaker than a line explaining what can move. A proforma invoice is a draft invoice issued before supply — for advance payment, customs or a client's internal approval — that is explicitly not a tax invoice and must not be booked as one.

Quote when the scope can be defined: measured work, listed materials, clear exclusions — most trade work qualifies, and clients prefer the certainty. Estimate when the scope genuinely cannot be known until opened up: fault-finding, concealed damage, ground conditions — and pair it with a daywork or unit-rate basis so the final number has an agreed engine, not an argument. Proforma when money or paperwork must move before the work: deposits on imported materials, a landlord's or bank's requirement, a client whose purchase-order process needs an invoice-shaped document first.

The chain should be one story: the accepted quote becomes the job; the job's invoices follow the quote's own structure — deposit, progress claims, final — so the client can trace every amount back to the document they accepted. A proforma is replaced by the real tax invoice when the supply happens; the proforma itself never enters the invoice sequence (see numbering done right).

In InstaJack the quote is the spine: it converts to the invoice with its lines and VAT treatment intact, so the promise and the bill are the same document at two moments in its life — which is most of paperwork discipline, done by construction.