Invoicing Software for Consultants

The three consulting billing models

Time and materials (T&M): You charge for actual hours at an agreed rate. Best for engagements with uncertain scope — advisory work, research, discovery phases. Requires disciplined time tracking and regular timesheet submissions. Invoice biweekly or monthly with a detailed hour log.

Fixed project fee: You agree on a total cost upfront, billed through milestone payments. Best for well-defined engagements — a strategy audit, a process redesign, a market analysis. Your margin depends on how accurately you scoped the work.

Monthly retainer: The client pays a fixed monthly fee for ongoing access to your time or a defined set of deliverables. Best for long-term advisory relationships. See the retainer billing setup guide for the complete structure.

Proposals and engagement letters

Consulting proposals serve a different purpose than agency proposals. You're not selling a tangible deliverable (a website, a campaign) — you're selling your thinking and your time. The proposal needs to demonstrate understanding of the client's problem, outline your approach (without giving away the solution), and present clear commercial terms.

For smaller or ongoing engagements, an engagement letteroften works better than a full proposal. It's a 2-3 page document confirming scope, fees, payment terms, confidentiality, and termination conditions. Lighter than a contract, more professional than an email. Send it the day the client agrees to proceed — don't let momentum die.

PropCraft's proposal generator supports both formats. Use the consulting template for formal proposals with cover letter, scope, timeline, and pricing. Use the custom template as a lightweight engagement letter. Either way, the client can accept digitally through the portal.

Professional invoicing that reflects your positioning

If you charge ₹10,000 per hour, your invoice should look like it comes from someone who charges ₹10,000 per hour. Clean formatting, your logo, consistent typography, clear line items, professional payment terms — these details reinforce the premium positioning that justifies your rates. A Google Sheets invoice with misaligned columns sends the wrong signal.

For T&M billing, your invoice should include a detailed time log: date, task description, hours. Attach it as a separate page or integrate it into the invoice line items. Clients paying hourly rates want transparency — show them exactly what they're paying for. For fixed-fee milestones, reference the specific deliverable: "Strategy phase — competitive analysis and recommendations deck delivered."

GST and tax compliance for consultants

Consulting services fall under SAC code 998361 (management consulting) or 998397 (other professional services) for GST purposes. The standard rate is 18%. If you're registered under GST, your invoice must include all mandatory fields: GSTIN, SAC code, place of supply, tax breakup, and total in figures and words.

For international consulting engagements, issue export invoices under LUT with zero-rated IGST. Bill in the client's currency and convert to INR for your records. Read the full GST guide for the filing and compliance details.

Payment tracking across multiple engagement types

When you have a mix of retainer, project, and hourly clients, payment tracking gets complicated. You need to know: which retainer invoices are overdue, which project milestone payments are pending, and what your total outstanding receivables look like across all engagement types. A dashboard that aggregates this across all clients — with status filters and automated reminders — replaces the spreadsheet you've been pretending is adequate.

Frequently asked questions