You built the model. Do you still own it after the client pays?

Maybe. It depends on what you signed, and client contracts often say more than consultants realize.

The default helps you

Without a written agreement, an independent contractor generally owns the copyright in what they create. A client who pays gets the deliverable and usually an implied right to use it, not ownership of your underlying methods.

The contract usually changes the default

Client paper often includes "work made for hire" language, a broad assignment of "all work product," or both. Read literally, that can hand over your spreadsheet engine, your templates, and anything you developed during the engagement.

Separate what you bring from what you build

A good agreement draws the line:

• Pre-existing materials. Your tools, templates, models, and know-how. You keep them.

• Deliverables. What the client paid for. They own it or get a broad license.

• The overlap. Your pre-existing material embedded in a deliverable. The client gets a license to use it as part of the deliverable; you keep ownership.

• General skills. You can keep doing the kind of work you do.

Watch the rest of the agreement

Confidentiality clauses can restrict reuse even when ownership doesn't. Non-solicitation and non-compete language can restrict who you work for next. Do you need a written contract with your clients? Yes, and this is a big reason why.

What to do

Use your own agreement when you can, with the pre-existing materials carve-out built in. When the client insists on theirs, find the ownership and confidentiality sections first and mark them up. Document review and revision covers either.

This is general information, not legal advice for your situation. If you want an answer for your business, book a consultation.