How to Invoice for Hours Worked

Reconcile the time record

Select entries from the correct client, project, and billing period. Remove duplicate timers, complete missing descriptions, and confirm that every included activity is covered by the agreement.

Check project caps, retainers, included hours, and previous invoices before billing. The uninvoiced total should represent new, approved work rather than all time ever recorded on the project.

• Filter the correct billing period
• Review billable status and approvals
• Remove duplicates and overlaps
• Exclude previously invoiced time

Calculate hourly charges

Multiply the approved duration by the agreed rate for each service or role. Apply the billing increment and rounding policy consistently, then sum the line totals and verify the arithmetic.

Handle discounts, retainers, taxes, and reimbursable costs as separate, clearly labeled calculations. Do not change an hourly rate on the invoice unless the client has already accepted that rate.

• Use the accepted rate
• Apply one consistent time increment
• Calculate each line independently
• Separate discounts, taxes, and expenses

Write useful invoice line items

Group entries according to the detail promised to the client. A line can represent a service, phase, role, or date range as long as the client can understand what was delivered.

For each line, show the description, hours, rate, and amount. Add the project name and service period, and avoid vague labels such as “miscellaneous work” or unexplained blocks of time.

• Name the service or project phase
• Show hours and hourly rate
• State the service period
• Use descriptions tied to outcomes

Send and preserve supporting records

Add the invoice number, issue date, due date, payment method, and agreed payment terms. Attach or link the client-facing timesheet when required, while keeping private internal notes out of the shared document.

After sending, mark the source entries with the invoice number and preserve the approved version. Track payment against the invoice rather than editing billed hours to reflect when money arrives.

• Include number and payment terms
• Attach agreed supporting detail
• Mark time entries as invoiced
• Keep the approved source record

Identify the period and approved work

Check whether you bill weekly, monthly or at a milestone. Select the relevant dates and exclude records already invoiced. Keep unapproved or disputed entries visible separately rather than silently including them in an apparently settled total.

Show the service period on the invoice. Even when the monthly amount is similar, the period helps the client match it to their budget, approvals and previous payments.

Calculate different rates separately

For an illustrative example, four hours of design at 220 cost 880, while 1.5 hours of meetings at an agreed 180 cost 270. The subtotal before tax is 1,150. This assumes both activities and rates were agreed as billable.

Do not add all hours and multiply by an unexplained average. Separate ordinary and special rates, roles or tasks when that distinction affects the charge.

Convert minutes correctly and apply agreed rules

Ninety minutes is 1.5 hours. A time notation such as 1:30 is different from the decimal number 1.30. Check the format your spreadsheet or application uses before multiplying time by a rate.

If the agreement includes minimum units or rounding, use that method consistently and retain the actual time where appropriate. Do not decide the method only when preparing the invoice.

Summarize on the invoice and support with a timesheet

You can group similar work at the same rate, such as a month’s maintenance, while a relevant attachment shows dates and tasks. The supporting hours and amounts must add up to the invoice.

Include only the client’s relevant records. Remove other clients’ data and internal personal notes from the shared version. A clear reference connects the attachment to the invoice without filling the main page with unnecessary detail.

Account for fixed fees and prepayments

List a fixed service fee separately from approved hourly extras. Show deposits or prepaid amounts applied to the invoice and display the remaining balance. If the client purchased a time allowance, explain usage and the remaining allowance according to the agreement.

Do not restart a prepaid balance from zero each month or deduct the same deposit repeatedly. Keep the time records, amounts charged and available credit connected.

Resolve a question at the task level

If the client queries a few hours, ask which date, task or rate needs explanation. Provide the relevant record and compare it with the agreement. Correct actual errors and preserve the adjustment history.

After invoicing, mark the used records and update payment status as money arrives. This prevents the same hours from reappearing on the next invoice and keeps reminders aligned with the real balance.