Time & Materials Billing: The Workflow That Eliminates Missed Hours

In an IT staffing firm, every hour a consultant works on an engagement has a value. At the average daily rate on the French market (between EUR 400 and 700 depending on the profile and industry), a single forgotten day represents a net loss of several hundred euros. Multiply that error by the number of consultants, by the frequency of oversights, by 12 months -- and you get a silent financial drain that most IT staffing firms don't even measure.

Time and materials billing should be mechanical. The consultant works, the time is tracked, the timesheet is validated, the invoice is issued, and payment is collected. Five linear steps, no surprises. Yet in practice, this process is riddled with leak points: unlogged days, late timesheets, invoices issued without verification, forgotten follow-ups. Each of these leak points costs money -- and the accumulation of these micro-losses can represent hundreds of thousands of euros per year for a mid-size IT staffing firm.

This guide describes the complete time and materials billing workflow, step by step, with the checkpoints that eliminate oversights. No theory. Concrete processes, calculations, and checklists.

The Cost of a Forgotten Hour in Time & Materials (Daily Rate x Frequency)

Before detailing the workflow, let's set up the calculation. How much does a billing oversight actually cost?

The Unit Calculation

Take a consultant billed at EUR 500 daily rate (a mid-level profile, 3-5 years' experience, IT sector). One forgotten workday -- not logged by the consultant, not caught by the manager, not billed to the client -- represents a EUR 500 loss.

But a forgotten day isn't an isolated event. Internal studies conducted by IT staffing firms that have measured this phenomenon show recurring numbers:

Key figure: on average, an IT staffing firm without a structured workflow loses between 0.5 and 1 billable day per consultant per month to entry omissions, assignment errors, or unrecovered billing delays.

The Annual Projection

Let's take the conservative estimate: 0.5 forgotten days per consultant per month.

With the high estimate (1 forgotten day per consultant/month):

For a 50-consultant firm with an average daily rate of EUR 550, the calculation gives:

• Conservative estimate: 50 x 0.5 x EUR 550 x 12 = EUR 165,000 per year
• High estimate: 50 x 1 x EUR 550 x 12 = EUR 330,000 per year

Concrete example: a 45-consultant IT staffing firm in Nantes audited its billing over 6 months. Result: 38 days of actual work not billed over the period, including 22 days not logged by consultants, 9 days logged but not included in the timesheet (compilation error), and 7 days billed but against the wrong purchase order (rejected by the client and never rebilled). At the average daily rate of EUR 520, the loss amounted to EUR 19,760 over 6 months, or nearly EUR 40,000 annualized. The firm implemented a structured workflow and reduced this loss to less than EUR 3,000 the following year.

These numbers aren't dramatic for a healthy IT staffing firm. But they represent net margin that evaporates for no reason. And above all, they're avoidable with a rigorous process.

The 5-Step Workflow: Entry, Validation, Timesheet, Billing, Collection

The time and materials billing workflow has five sequential steps. Each step has an owner, a frequency, deliverables, and checkpoints. If any step fails, the following ones are compromised.

+--------------+    +--------------+    +--------------+    +--------------+    +--------------+
|  STEP 1      |    |  STEP 2      |    |  STEP 3      |    |  STEP 4      |    |  STEP 5      |
|  Daily       |--->|  Manager     |--->|  Monthly     |--->|  Billing     |--->|  Payment     |
|  entry       |    |  validation  |    |  timesheet   |    |              |    |  follow-up   |
|              |    |              |    |              |    |              |    |              |
|  Who:        |    |  Who:        |    |  Who:        |    |  Who:        |    |  Who:        |
|  Consultant  |    |  Eng. mgr    |    |  Admin/CFO   |    |  Admin/CFO   |    |  Admin/CFO   |
|              |    |              |    |              |    |              |    |              |
|  When:       |    |  When:       |    |  When:       |    |  When:       |    |  When:       |
|  Every day   |    |  Every week  |    |  D+1 to D+3  |    |  D+3 to D+5  |    |  Ongoing     |
+--------------+    +--------------+    +--------------+    +--------------+    +--------------+

Step 1: Daily Entry by the Consultant

The consultant logs their time every day. This is the foundation of the entire process. Without entries, there's nothing to validate, nothing to compile, nothing to bill.

Daily entry in time and materials is straightforward: the consultant confirms their attendance (full day, half day, or absence). The action takes less than 30 seconds if the engagement is pre-assigned in the tool.

Success conditions:

• The engagement is pre-configured (no searching through a dropdown menu)
• The tool is accessible on mobile (the consultant is at the client's office, not at headquarters)
• An automatic reminder is sent at end of day if the entry hasn't been made
• Entry is possible in 1-2 clicks for the standard case (full day)

Key takeaway: Daily entry isn't an act of discipline imposed on the consultant. It's an act of financial protection for the firm. Every unlogged day is a potentially unbilled day. The difference between a profitable IT staffing firm and one that loses money often comes down to this level of granularity.

Step 2: Validation by the Engagement Manager

Each week, the engagement manager reviews their consultants' entries. This check takes 2 to 5 minutes per consultant and covers four points:

1. Completeness. Are all business days for the week logged? Empty days should be identified and the consultant followed up with immediately -- not at month-end when memory has done its work of erasure.

2. Consistency. Is the entry consistent with the known schedule? If the consultant is supposed to be on leave on Friday, they shouldn't have logged a full day.

3. Correct assignment. Is the consultant logging against the right engagement? If a consultant switched clients mid-month or works on a split assignment, assignment errors are common.

4. Volume. Is the number of days logged consistent with the contract? A full-time consultant should log 5 days per week (excluding absences and public holidays). Fewer than 4 days logged in a standard week should trigger a check.

Common mistake: not validating at all during the month and discovering problems on the 1st of the following month, when compiling timesheets. Weekly validation prevents the "end-of-month surprise" effect that delays billing by 5 to 10 days.

Step 3: Monthly Timesheet Generation

On the last business day of the month (or the first of the following month), the timesheet is generated. If steps 1 and 2 were correctly executed, this operation is nearly automatic: the data is complete, verified, and correctly assigned. All that remains is exporting it in the format expected by each client.

The monthly timesheet must then be:

• Sent to the client for validation (with the consultant's signature)
• Tracked until client validation is obtained
• Archived as supporting documentation for the invoice

Target timeline: the timesheet should be sent to the client before the 3rd of the following month. Any delay beyond the 5th exposes the firm to rejection or billing deferral, depending on the client's contractual requirements.

Step 4: Invoice Issuance

Once the timesheet is validated by the client, the invoice can be issued. This step is often handled by the administrative department or CFO, but it depends on the quality of data produced by the preceding steps.

The time and materials invoice includes:

• The contract or purchase order reference
• The number of days billed (matching the validated timesheet)
• The contractual daily rate
• The total amount excluding and including tax
• The validated timesheet reference as an attachment

Pre-issuance verification checklist:

Key figure: IT staffing firms that issue their invoice within 5 days of timesheet validation reduce their average collection time by 12 days compared to those that invoice in the middle of the following month. The effect is mechanical: the sooner the invoice goes out, the sooner it's paid.

Step 5: Payment Tracking and Follow-Up

The invoice is issued. The job isn't done. Without tracking, payment timelines drift. A client that usually pays in 30 days starts paying in 45, then 60, without anyone noticing.

Payment tracking involves:

• Recording the issue date and due date (30 days end of month, 45 days, per contract)
• Verifying collection at maturity: bank reconciliation
• Following up on D+1 past due: a polite email reminding of the unpaid invoice
• Escalating at D+15 past due: follow-up with the commercial contact on the client side
• Alerting management at D+30 past due: decision on next steps (formal notice, service suspension)

Key takeaway: Follow-up isn't a confrontational act. It's a normal business management action between professionals. An email on D+1 past due is enough in 70% of cases to trigger payment. Most delays aren't intentional: they result from an oversight on the client side, a slowed internal approval process, or a missing document in the file.

Checkpoints for Zero Leakage

The 5-step workflow is the standard process. But billing leaks occur in the gaps -- between steps, in edge cases, in exceptions nobody planned for.

Here are the specific checkpoints that plug these leaks:

Checkpoint 1: Weekly Entry Rate

Every Friday (or Monday morning at the latest), check the previous week's entry rate. The target is 100%: all consultants have logged all their business days for the week.

A rate below 90% is a warning sign. A rate below 80% is a structural problem requiring immediate action (individual follow-up, verifying the tool is functional, meeting with the consultants involved).

Checkpoint 2: Business Days vs Logged Days Reconciliation

Each month, verify that total days logged per consultant is consistent with the calendar:

Business days in the month
- Leave days taken
- Public holidays
- Sick days
- Bench days
= Expected billable days

Compare with: Days actually logged
Acceptable variance: +/- 0.5 day (half-day rounding)

Any variance greater than 0.5 day should be investigated before generating the timesheet.

Checkpoint 3: Timesheet vs Invoice Reconciliation

After issuing the invoice, verify that the number of days billed exactly matches the validated timesheet. This check seems basic, but entry errors between the timesheet and the invoice (manual re-entry, calculation mistakes) are a frequent source of client rejections.

Checkpoint 4: Order Tracking

For each active engagement, track purchase order consumption:

Concrete example: a Bordeaux-based IT staffing firm discovered, when implementing this checkpoint, that 3 of its 18 engagements had exceeded their purchase order without anyone noticing. 14 days of actual work hadn't been billed because the purchase order was exhausted and renewal hadn't been requested. Loss: 14 x EUR 480 = EUR 6,720. A monthly check would have caught the overrun 2 months earlier.

Checkpoint 5: Billing vs Collection Reconciliation

Each month, verify that all invoices issued the previous month have been paid or are within their payment terms. Invoices unpaid past their due date must be systematically followed up.

Automating the Detection of Unbilled Time

The final link in the workflow is proactively detecting time that risks never being billed. These "orphan" hours exist in every IT staffing firm, but most have no way to identify them.

Sources of Unbilled Time

The Monthly Detection Report

To identify this unbilled time, a monthly report should answer five questions:

1. Which consultants have unlogged days? Compare the month's business days with days actually logged. Any gap not explained by an absence is a potentially unbilled day.

2. Which days are logged but not validated? These entries are awaiting manager verification. The longer they wait, the higher the risk of being forgotten.

3. Which timesheets haven't been sent to the client yet? If the 5th of the following month has passed and a timesheet hasn't been sent, a billing delay is forming.

4. Which sent timesheets haven't been validated by the client yet? These timesheets need a follow-up with the client contact.

5. Which validated timesheets haven't resulted in an invoice yet? This is the last leak point: the timesheet is ready, but nobody triggered the billing.

Key takeaway: Detecting unbilled time isn't an annual audit. It's a 30-minute monthly check that reviews the entire pipeline: entry -> validation -> timesheet -> invoice -> payment. Every step without a completed deliverable is a potential leak point.

The Billing Dashboard

The ideal dashboard for time and materials billing management displays in real time:

• Revenue billed this month: total amount of issued invoices
• Revenue pending timesheet: days worked for which the timesheet isn't yet validated
• Revenue pending billing: validated timesheets for which the invoice hasn't been issued yet
• Accounts receivable: issued invoices not yet paid, with aging (0-30 days, 31-60 days, 61-90 days, >90 days)
• Leak rate: percentage of worked days not billed for the month (target: < 1%)

This dashboard transforms billing from a reactive process ("we bill when we think about it") into a managed process ("we know exactly what's billed, what's pending, and what's at risk of being lost").

The Monthly Control Checklist

To summarize the entire workflow, here's the checklist the billing manager should follow each month:

• D+1: Check the entry rate for the past month (target 100%)
• D+1: Follow up with consultants who have unlogged days
• D+2: Verify that the manager has validated all entries
• D+3: Generate timesheets for all consultants
• D+3: Check the business days vs logged days reconciliation
• D+3: Send timesheets to clients for validation
• D+5: Follow up with clients who haven't validated timesheets
• D+5: Issue invoices for validated timesheets
• D+5: Verify the timesheet vs invoice reconciliation
• D+5: Check purchase order consumption
• D+10: Follow up on timesheets not yet validated
• D+10: Check overdue payments from the previous month
• D+10: Follow up on unpaid invoices
• End of month: Generate the unbilled time detection report

Key figure: IT staffing firms that apply this monthly checklist reduce their billing leak rate to less than 0.5% of worked days. For a 30-consultant firm at an average daily rate of EUR 500, that's the difference between losing EUR 90,000 per year (3% leak rate) and losing less than EUR 15,000 (0.5% leak rate).

Time and materials billing isn't an accounting topic. It's a process topic. Every day a consultant works follows a five-step path -- entry, validation, timesheet, billing, collection -- and each step is a potential leak point. The workflow described in this guide doesn't eliminate the risk of human error. It contains it, detects it, and corrects it before it becomes lost revenue.

The first step is always the same: ensuring every consultant logs their time, every day. The rest of the workflow -- validation, timesheet, billing, follow-up -- is simply a logical succession of checks and actions triggered by that daily entry. Without it, the entire process relies on memory and goodwill. With it, it relies on data and controls. The difference, for an IT staffing firm of 20 to 50 consultants, amounts to tens, sometimes hundreds of thousands of euros per year.