Onboarding contractors is usually described from the legal side, and this page describes it from the operations side: what actually has to happen between a signed agreement and a first invoice being paid without argument, and which two steps cause most of the delay. Nothing here is advice on classification or on what your firm must collect, which are questions for your firm and its counsel.
The sequence, from the operations desk
Agreement signed. Identity and tax details collected, which for a US contractor means Form W-9. Payment details recorded. Access requested. Start date confirmed with a named contact on your side. First work done. First invoice received, checked against the agreed rate and basis, and paid. Seven steps, each with an owner, and the whole thing is a checklist rather than a project.
Delay one: access
Access requests leave the onboarding conversation and enter somebody else's queue, usually somebody who has no idea a contractor is waiting. This is the single most common reason a contractor with complete paperwork cannot begin, and the fix is to raise them on day zero in parallel with everything else rather than once the paperwork is finished.
Delay two: the invoicing mismatch
The first invoice arrives in a format nobody agreed, for a rate expressed differently from the agreement, and sits unpaid while two people work out whether it is right. Agreeing the invoice format and the rate basis in writing during onboarding costs five minutes and removes a fortnight of politeness later.
What to record and why
What you collected, when, and from whom. Not because a checklist proves anything about your obligations, but because the operational question, has this contractor been onboarded, needs an answer that is not somebody's recollection.
Questions people ask about onboarding contractors
How is this different from onboarding a client?
The shape is identical and the documents differ. The money flows the other way, which is why the invoicing agreement matters more here.
Who should own contractor onboarding?
The same person or list that owns client onboarding. Two parallel processes in one firm diverge and only one stays current.
Does this cover employees?
No. Employee onboarding is a different regime and a different hub; this is the counterparty paperwork a firm's operations desk runs.