Consulting Agreement

What this document is

Consulting work sells knowledge rather than a fixed deliverable, and that changes what the contract has to do. A consulting agreement records the kind of advice or expertise you provide, how your time is billed — hourly, daily, or as a monthly retainer — and the rhythm of invoicing and payment. It suits marketing advisors, IT and business consultants, trainers, and anyone whose value is their judgment rather than a file they hand over.

Because there is often no single 'finished product', the biggest risks are open-ended: engagements that drift on with no clear end, retainers a client stops paying but keeps calling, and confidential business information flowing in both directions. This agreement puts boundaries around all three — a defined term, payment due dates with consequences, and a confidentiality clause that survives the engagement.

When to use it

• A business wants your advice on a recurring basis and you are agreeing a monthly retainer.
• You charge by the hour or day and need the rate, minimum billing, and expense rules in writing.
• An engagement will run for months and either side should be able to exit with proper notice.
• The client will share sensitive numbers or plans with you and wants confidentiality agreed.
• You are the business hiring a consultant and want fees and deliverables predictable from the start.

When not to use it

• The work is really a defined project with concrete deliverables — a freelance service agreement fits that shape better.
• The client expects fixed working hours under their supervision; that pattern looks like employment and deserves proper advice before you sign anything.
• The advice touches regulated fields — legal, audit, medical, licensed financial advice — where professional-body rules govern the engagement terms.
• You are joining as a director or partner rather than an outside advisor; that relationship needs different documents entirely.

Information you will need

• Full names and ID or company registration details of consultant and client
• A description of the consulting services and the areas they cover
• The fee basis: hourly rate, day rate, or monthly retainer amount
• What a retainer includes (hours, response time) and what falls outside it
• Invoicing cycle and payment due date — for example, invoices monthly, payable within 15 days
• Which expenses are reimbursable and whether they need advance approval
• Start date, duration, and the notice period for ending the engagement
• Confidentiality expectations on both sides

Clauses included

How to sign it

Sign before the first billable session, and before the first retainer payment if there is one — the payment then confirms the terms rather than preceding them. Each side keeps a signed copy; a PDF signed and exchanged by email is standard for consulting engagements.

For retainer arrangements, keep the signed agreement alongside a simple log of hours or sessions delivered each month. If a client ever questions what the retainer bought, the log answers it in seconds.

When the engagement is extended or the rate changes, do not rely on a chat message — record the change in a short signed amendment so the paper always matches what you are actually billing.

Common mistakes

• Leaving 'consulting services' undefined, so every phone call, message, and meeting is arguably included in the fee.
• No minimum billing unit — a rate of THB 2,000 per hour means little if ten-minute calls are free.
• Letting a retainer roll on month to month with no notice period, then losing a month's income overnight when the client cancels.
• Failing to say whether unused retainer hours carry over or expire.
• Continuing to advise while invoices pile up unpaid, instead of pausing under the contract after the first overdue notice.
• No confidentiality clause protecting you when the client shares another company's information with you.

Frequently asked questions