How to Invoice for Hours Worked: Time Billing Made Simple

When to Bill by the Hour

Hourly billing suits work where the scope is difficult to define upfront, where the time required varies significantly, or where clients want flexibility to adjust as the project evolves.

Common hourly-billed professions: consulting, legal, accounting, design, development, copywriting, photography, trades (plumbing, electrical, building), coaching.

The alternative — fixed-price billing — works when scope is clearly defined. Many businesses use both: fixed price for well-defined deliverables, hourly for open-ended or advisory work.

Tracking Your Hours

Accurate hourly invoicing starts with accurate time tracking. Methods:

Time-tracking app: Toggl, Clockify, and Harvest are popular free and low-cost options. Start a timer when you begin work, stop when you finish. The app logs billable hours per project and client automatically.

Spreadsheet timesheet: Date, client, project, hours worked, description. Simple and sufficient for lower volumes.

Physical timesheet: Works for trades who are on-site — note start time, end time, and task for each visit.

Whatever method you use, record hours the same day. Reconstructing a week of hours on Friday afternoon leads to under-billing and inaccurate records.

What to Include on an Hourly Invoice

Your invoice should show:

Hourly rate: Your agreed rate per hour (e.g. $120/hr)

Hours worked: Total hours billed — ideally with a breakdown by date or task

Time period covered: The date range the invoice covers (e.g. 1–31 May 2025)

Calculated total: Hours × Rate = Amount

Description: What the hours were spent on

Example line item:

"Digital marketing consultancy — 14 hours × $120/hr — May 2025 — $1,680"

For larger invoices or clients who want detail, provide a timesheet attachment or a line-by-line breakdown.

Providing a Timesheet with Your Invoice

For clients who require it (and for your own protection), attach a timesheet showing:

| Date | Description | Hours |

| 1 May | Strategy meeting — 2hrs |

| 3 May | Keyword research — 3hrs |

| 7 May | Content calendar creation — 4hrs |

This level of detail removes any ambiguity and makes disputes virtually impossible if the client approved the work.

Rounding and Minimum Charges

Decide upfront how you handle short time increments:

Round to nearest 15 minutes: Common for most professionals

Round to nearest 30 minutes: Simpler, slightly less precise

Minimum charge per visit/call: Many consultants and trades charge a minimum of 1 hour per engagement (e.g. a 20-minute site visit is billed as 1 hour)

State your rounding and minimum charge policy in your initial agreement — not on the invoice after the fact.

Getting Approval Before Billing

For ongoing time-billed engagements, consider a monthly approval process:

Send a draft timesheet to the client showing hours for the month

Client reviews and approves (or raises any questions)

You issue the invoice against the approved timesheet

This eliminates billing disputes because the client has signed off on the hours before the invoice arrives.

Capping Hourly Work

For clients who are nervous about open-ended hourly billing, offer a monthly cap: "I'll bill at $150/hr up to a maximum of 20 hours per month ($3,000). Any additional hours require your approval."

The cap gives the client budget certainty while preserving hourly billing flexibility for you.

Invoicing for Hours in Quotation Expert

In Quotation Expert, add a line item with the description of work, quantity (hours), unit price (your hourly rate), and the total calculates automatically. For clients who need a timesheet, attach it to the PDF or paste the breakdown in the description field. Your full invoice history by client shows all hourly billing over time — useful for performance reviews and rate negotiations.