A timer proves that time was recorded. It does not prove that the time belongs on a customer's invoice. Billable status depends on the client agreement, work source, approval state, rate and period.
The safest workflow preserves recorded time even when it is excluded from billing. That distinction protects the operating record without turning every valid hour into a customer charge.
Define the states before calculating
Recorded means the work entry exists. Submitted means it is ready for a defined review. Approved for billing means an accountable person has confirmed the client, project, billable status and period.
Use separate states rather than one editable flag. A clear transition history shows who changed the decision and when.
Attach the rate after approval context is known
A person's default rate may differ from the rate agreed for a client, project, service or time period. Resolve the applicable rate from the commercial record rather than the timer profile.
Retain the rate source with the invoice input. If a reviewer changes it, capture the exception rather than silently overwriting the original.
Handle excluded time without deleting it
Internal, non-billable or rejected time can still be valid project evidence. Keep it in the work record with a reason, while preventing it from entering the invoice calculation.
This separation lets teams review delivery effort and billing outcomes without confusing utilisation, revenue and customer charges.
Reconcile the period before sending
Check for late entries, duplicate imports, entries outside the billing period and time already billed. The invoice should use a closed, reproducible set.
After approval, changes should reopen the relevant control instead of altering an already reviewed total in place.
Translate the commercial agreement into time rules
Billable time begins with the agreement. Identify which roles, activities, projects and periods are chargeable; whether approval is required; which minimum increments or caps apply; and how rates change over time. Do not rely on one global billable flag when the same person's work may be billable for one client and excluded for another. Effective dates matter because a valid new rate should not rewrite earlier periods.
Keep the rule close to the source entry. A reviewer should be able to see the person, date, project, work description, duration, billable decision, approval state and applicable rate source. Sensitive operational notes need not appear on the customer invoice, but the retained description must still explain why the work belongs to the billed engagement. Generic labels make later review and disputes needlessly difficult.
Create a controlled approval sequence
A practical sequence moves time from recorded to submitted, approved for delivery where required, approved for billing and included in an invoice period. These states answer different questions. Delivery approval confirms that work occurred or met a project standard. Billing approval confirms that the customer can be charged under the commercial rule. Combining the two may be appropriate for a simple engagement, but the authority and decision should remain explicit.
Returned entries should retain the reason and correction owner. If the date, project or duration is wrong, correct the entry without erasing the original. If the work is valid but non-billable, preserve it as excluded with the applicable reason. If approval arrives after the billing cut-off, apply the documented late-entry rule rather than inserting the time into an already reviewed invoice without reopening control.
Calculate one reproducible invoice input
Close the billing period before calculation. Check duplicate imports, overlapping entries, missing descriptions, unapproved time, work outside the date range and entries already billed. Group only after the eligible set is fixed. For example, 38 approved hours at an applicable client rate can form an invoice input while eight internal hours remain in the project record and out of the charge.
Retain enough detail to reproduce the result after the invoice is sent. That includes the approved-entry identifiers, total approved quantity, rate and rate source, rounding rule, invoice line and invoice version. If the customer sees a summarised line, finance should still be able to move from that line back to the approved work without searching several exports or relying on one employee's memory.
Treat corrections as controlled events
Corrections can change duration, classification, project, rate or approval. Record which fact changed, the previous value, the new value, reason, authority and effective period. A correction before sending can create a new reviewable invoice version. A correction after sending needs the approved document-correction process and should never make the original issued record disappear.
Separate billing correction from accounting treatment. The billing record explains the source work, approval and customer-facing amount. The accounting system remains responsible for ledger entries, revenue policy and statutory reporting. Stable invoice and work identifiers allow both systems to stay consistent without collapsing their responsibilities.
Review the process with operating measures
Measure recorded-to-submitted, submitted-to-approved and approved-to-invoiced time separately. Also review return reasons, late entries, excluded hours, rate overrides and corrections after review. These measures show where work is waiting and which rules cause repeated exceptions. They should be interpreted with engagement type and volume rather than used as an unsupported universal benchmark.
Choose one representative week and ask a second person to reproduce the invoice input. They should identify the eligible entries, explain every exclusion, find the applicable rate and confirm the approval history. If they cannot, improve the retained facts and decision states before adding automation. Faster calculation is useful only after the result is commercially defensible.
Decision summary
Keep the commercial trigger and source evidence visible for every material charge.
Separate preparation, review, correction, sending and accounting responsibilities.
Retain versions, reasons, owners and timestamps whenever a decision changes.
Test the control with one difficult invoice another authorised person can reproduce.
Separate customer explanation from internal evidence
The outgoing invoice should explain the charge at the level agreed with the customer. It may summarise approved work by project, role, task group or period, while the internal record retains entry-level evidence. Do not publish sensitive internal notes merely to prove detail, and do not remove so much context that the customer cannot understand what the amount represents.
Align the summary with the agreement and approval record. If the customer requires named resources, purchase-order references or service descriptions, carry those facts into the invoice version before outgoing review. The internal evidence and customer document serve different audiences, but stable identifiers should connect them so a question can move from the invoice line to the authorised work set without interpretation.
Put the control into practice
Test the process with one week containing billable and excluded work. A second person should be able to reproduce the invoice input from the retained entries, approval and rate source.
Run the review on a real case
A consultant records 46 hours, of which 38 are client-approved and eight are internal or excluded. The invoice uses only the 38 approved hours at the applicable client rate. The other eight hours remain valid work records without becoming customer charges.
Reproduce the calculation from person, project, period, approval state and rate source. If a correction changes approved hours or rate, preserve the earlier value, correction reason, approver and resulting invoice version.
Case-review checklist
Time period and project are identified
Recorded and approved states stay separate
Exclusions keep their original reason
Client rate has an effective boundary
Correction history remains inspectable
A time tracker proves that time was recorded, not that the customer can be billed. The commercial agreement and approval decision remain the authority for invoice preparation.
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