Project Billing - T&M is where ERP discipline either begins or breaks.
Time and Material (T&M) Project Billing with Approved Timesheet Integration looks operational from far away. In a real finance team, it is a chain of assertions: the right actor started the work, the required records existed, the control policy was applied, the state change was preserved, and the outcome can be explained later without rebuilding the transaction from emails and spreadsheets.
The expected business outcome is specific: Invoice cycle time under two business days from period close; WIP balance reconciles to zero after invoicing; billing disputes resolved within contractual SLA.
The control flow a finance team actually needs.
Step 1
Timesheet-To-Invoice Traceability At...
Step 2
Multiple Bill Rates Per Labor Category...
Step 3
Split-Billing Across Multiple Customers...
Step 4
Approved Timesheet Entries Locked From...
Step 5
Invoice Released Only After PM Approval
The ERP surface involved.
Module
Project Billing - T&M
Actors
Consultant, Project Manager, Billing Clerk, Customer
Tier
Tier 1
Finance area
Project & Service Management (PSA) and Revenue Recognition
Region lens
US and UK finance teams
Publication date
June 4, 2026
Timesheet-to-invoice traceability at line level; support multiple bill rates per labor category per project; split-billing across multiple customers on one project; approved timesheet entries locked from further editing without audit trail; invoice released only after PM approval; WIP balance updated within one business day of invoice posting; support invoice-level and line-level hold.
US and UK teams have different compliance hooks, but the same control problem.
US teams usually care about clean evidence for audit support, vendor records, payment controls, tax reporting, and management review. UK teams usually care about VAT-ready records, approval evidence, digital-record discipline, and traceable postings. The country-specific details differ, but the operating pattern is the same: the ERP needs controlled records, explicit ownership, defensible state changes, and evidence that survives beyond the person who completed the task.
The control matrix.
| Control area | Requirement | Acceptance proof |
|---|---|---|
| Control 1 | Timesheet-to-invoice traceability at line level | Given approved timesheet entries tagged to project tasks with contractual bill rates by labor category |
| Control 2 | support multiple bill rates per labor category per project | when the billing clerk generates the draft invoice and releases it after PM approval |
| Control 3 | split-billing across multiple customers on one project | then the invoice reflects correct hours, applied rates, and expense reimbursements, WIP balances decrease by the invoiced amount, and all lines are traceable to approved timesheet entries |
| Control 4 | approved timesheet entries locked from further editing without audit trail | negative) when an invoice is released without PM approval then the system rejects with 403 and error code INVOICE_APPROVAL_REQUIRED. |
| Control 5 | invoice released only after PM approval | Invoice cycle time under two business days from period close; WIP balance reconciles to zero after invoicing; billing disputes resolved within contractual SLA. |
| Control 6 | WIP balance updated within one business day of invoice posting | Invoice cycle time under two business days from period close; WIP balance reconciles to zero after invoicing; billing disputes resolved within contractual SLA. |
Audit evidence is a chain, not a folder.
| Evidence layer | What should be preserved |
|---|---|
| Business event | Consultants submit weekly timesheets tagged to project tasks. Project managers approve or reject individual time entries. Approved hours flow into the billing module where the ERP applies contractual bill rates by labor category. The billing clerk reviews the draft invoice, adds expense reimbursements, and releases the invoice to the customer. The ERP posts revenue to the appropriate period and updates unbilled work-in-progress (WIP) balances. |
| Control rules | Timesheet-to-invoice traceability at line level; support multiple bill rates per labor category per project; split-billing across multiple customers on one project; approved timesheet entries locked from further editing without audit trail; invoice released only after PM approval; WIP balance updated within one business day of invoice posting; support invoice-level and line-level hold. |
| Acceptance proof | Given approved timesheet entries tagged to project tasks with contractual bill rates by labor category; when the billing clerk generates the draft invoice and releases it after PM approval; then the invoice reflects correct hours, applied rates, and expense reimbursements, WIP balances decrease by the invoiced amount, and all lines are traceable to approved timesheet entries; (negative) when an invoice is released without PM approval then the system rejects with 403 and error code INVOICE_APPROVAL_REQUIRED. |
| Data record | |
| System event | |
| Lifecycle state | |
The useful version of this workflow is not only fast. It is inspectable. A controller, auditor, or operator should be able to move from source event to system record to state transition to final business outcome without guessing.
Implementation contracts.
Reference data model
`timesheet_entry` { external_id: string, consultant_id: string, project_id: string, wbs_element_id: string, date: date, hours: decimal, status: enum(DRAFT,SUBMITTED,APPROVED,REJECTED,LOCKED) }; `bill_rate` { external_id: string, project_id: string, labor_category: string, rate_minor: int64, currency_code: char(3), effective_date: date }; `project_invoice` { external_id: string, project_id: string, customer_id: string, status: enum(DRAFT,PENDING_APPROVAL,APPROVED,RELEASED,PAID,VOID), total_minor: int64, currency_code: char(3) }; `wip_balance` { project_id: string, period: date, balance_minor: int64, currency_code: char(3) }; (reference, product may differ).API and events
`POST /v1/timesheets` { external_id, consultant_id, project_id, wbs_element_id, date, hours } -> 201 { timesheet_id }; `POST /v1/timesheets/{id}/submit` -> 200; `POST /v1/timesheets/{id}/approve` -> 200 { locked: true }; `POST /v1/projects/{id}/invoices/generate` { period_end_date } -> 201 { invoice_id, lines }; `POST /v1/project-invoices/{id}/release` -> 200 { released_at }; `GET /v1/projects/{id}/wip-balance`; emits `project.invoice_released` and `project.wip_updated` events; idempotent via `external_id`.State transitions
`DRAFT -> SUBMITTED -> APPROVED -> LOCKED` (timesheet lifecycle); `DRAFT -> PENDING_APPROVAL -> APPROVED -> RELEASED -> PAID` (invoice lifecycle); terminal `VOID`; guard: APPROVED timesheet entry cannot be edited without audit trail; invoice cannot be RELEASED unless status is APPROVED.Common implementation traps.
Treating the workflow as data entry
If the ERP only stores the final record, the team loses the decision trail that explains how the record became valid.
Hiding exception logic
Exceptions need owners, reason codes, and time stamps. A vague pending state is not a control.
Posting without recovery design
Retries, duplicate submissions, and partial failures must be explicit so the system does not create inconsistent records.
Skipping evidence design
A workflow that cannot produce evidence on demand will eventually push finance teams back into manual screenshots and spreadsheets.
Where Rivane fits.
Rivane is built for finance workflows where automation must stay tied to source documents, approvals, state transitions, ledger impact, reporting, and audit evidence. Use this guide as a checklist for evaluating whether an ERP workflow is merely digitized or actually controlled.
References and source basis.
These sources provide the standards, regulatory, or government context around the flow. They are included so the guide is useful to finance operators, auditors, and implementation teams, not only buyers reading software copy.