Project Finance and Billing Teams
How do project-based businesses manage milestone billing and invoice compliance?
Project-based businesses (engineering, IT, construction, consulting) bill clients at project milestones or against time and materials. Each billing event creates a tax point requiring a compliant invoice. Milestone billing requires clear contract terms defining what triggers each invoice, and invoice descriptions must match the deliverable documented in the contract. Retentions held by clients create deferred invoice obligations.
How are project milestones structured for invoice compliance?
Milestone billing requires careful contract design and invoice timing:
- Milestone definition: Each milestone must be clearly defined in the contract (deliverable, acceptance criteria, amount)
- Tax point: Invoice issued when milestone is completed and accepted, not when the contract is signed
- Description: Invoice description must identify the milestone being invoiced, not just a generic 'consulting services'
- Retention: If contract includes retention, invoice for full milestone amount; show retention held as a deduction
- Application for payment: In construction, application for payment precedes the tax invoice; timing rules vary
- Variations: Variation orders create separate invoiceable events; each variation must be separately authorized
Frequently Asked Questions
- What is a retention and how is it invoiced?
- A retention is a percentage (typically 5-10 percent) of each progress payment that the client withholds until project completion or defects liability period expiry. The full invoice amount is raised at each milestone and the retention is deducted from the payment rather than from the invoice. VAT applies to the full invoice amount including the retained portion at the invoice date. The retention amount becomes payable (and a final invoice may be needed) when the retention release conditions are met.
- How do time and materials invoices comply with e-invoicing mandates?
- Time and materials invoices include multiple line items: hours by staff category at agreed rates, and materials at cost or with markup. Structured e-invoice formats (UBL, Factur-X) support line items with individual descriptions, quantities, unit prices, and VAT rates, making T&M invoices suitable for electronic format. The challenge is that T&M invoices often have many line items; ERP and project management systems must generate the structured XML from timesheet and expense data automatically.