How to Fill Out an Invoice: Box-by-Box Guide With Example
How to fill out an invoice box by box: what goes in each field, what to leave blank, a completed example and a checklist to catch errors before sending.
Quick answer: To fill out an invoice, work through the template from top to bottom: enter your business details, the client's Bill to details, a unique invoice number, the issue date and due date, then one line per product or service with a description, quantity and rate. Add any discount, tax and shipping, confirm the total due, fill in payment instructions and notes, and save the completed invoice as a PDF.
This is a box-by-box guide for anyone holding a template (printed, spreadsheet or online) and wondering exactly what goes where. We cover every common field, what you can leave blank, a completed example and a final checklist. The quickest way to follow along is in our free invoice generator, which has each of these boxes and calculates the totals as you type.
Before you start: gather this information
Filling out an invoice is fast when you have everything in front of you. Collect:
- Your business name, address, email, phone and tax ID (if registered)
- The client's legal name, billing address and email for invoices
- Any PO number or project reference the client gave you
- Dates the work was done or goods were delivered
- Quantities, hours or units and the agreed rates
- Your bank details or payment link
- The payment terms agreed in your contract or quote
If you're still choosing what kind of form to use, our blank invoice template guide compares printable and digital options.
How to fill out an invoice: box by box
Most invoice templates use the same fields in roughly the same order. Here's what to enter in each.
| Box | What to enter | Required? |
|---|---|---|
| Logo | Your business logo image | Optional |
| From / Your details | Business name, address, email, phone | Yes |
| Tax ID | EIN, VAT number, GST number, TRN or NTN if registered | If registered |
| Bill to | Client's legal name, address, email | Yes |
| Invoice number | Next number in your sequence | Yes |
| Invoice date | Date you issue it | Yes |
| Due date | Specific date payment is due | Strongly recommended |
| PO number | Client's purchase order reference | If the client uses POs |
| Line items | Description, quantity, rate (amount calculates) | Yes |
| Discount | Percentage or fixed amount | Optional |
| Tax rate | Rate you're registered to charge | If registered |
| Shipping | Delivery charge | Optional |
| Amount paid | Deposit already received | Optional |
| Notes / Terms | Payment instructions, terms, thanks | Yes |
| Signature | Your signature image | Optional |
Box 1: Your business details
Enter your name exactly as it appears on your contract or registration. Include the email address you want queries sent to. If you're registered for tax, add your tax ID in its own field; our guide to the tax ID on an invoice explains which number to use in which country.
Box 2: Bill to
Enter the business that pays, for example "Harbor Dental Group LLC", not "Dr. Lee". Use the billing address from the contract or PO. Add the accounts payable email if they gave you one.
Box 3: Invoice number
Enter the next number in your sequence. If this is your first invoice, you can start at any number, such as INV-0001 or 2026-101, as long as each following invoice goes up by one. The invoice number generator can suggest a format.
Box 4: Invoice date and due date
The invoice date is the day you issue it. For the due date, add your payment terms to the invoice date (Net 15 on an invoice dated 22 October 2026 means a due date of 6 November 2026) and enter that date.
Box 5: Line items
Fill one row per product or service. In Description, say what it is and when it was delivered. In Quantity, enter units, hours or days. In Rate, enter the price per unit. If the template doesn't calculate, multiply quantity by rate yourself and enter the amount. Billing by time? See how to invoice for hourly work.
Box 6: Discount, tax and shipping
Only fill these if they apply. Enter a discount as a percentage or fixed amount. Enter the tax rate only if you're registered to charge it, and make sure the document meets local rules. Our tax invoice guide lists the extra fields some countries require. Enter shipping if you're passing on delivery costs.
Box 7: Amount paid
If the client paid a deposit, enter it here so the invoice shows the balance due rather than the full total.
Box 8: Notes, terms and payment details
Write how to pay and where. For bank transfers, include the account name, account number and routing or sort code, or IBAN and SWIFT for international payments. See bank details on an invoice. Add the terms ("Payment due within 15 days") and a thank-you line.
Box 9: Signature and logo
Optional, but a logo makes the invoice recognizable and a signature adds a personal touch. Neither is usually a legal requirement.
Completed example: a filled-out cleaning invoice
From: Sparkle Pro Cleaning, 18 Elm Street, Springfield. Bill to: Harbor Dental Group LLC, 400 Bay Road, Springfield. Invoice: INV-2026-0127. Date: 22 October 2026. Due: 6 November 2026 (Net 15). PO: HDG-3381.
| Description | Qty | Rate (USD) | Amount (USD) |
|---|---|---|---|
| Weekly office cleaning, October 2026 (visits) | 4 | 165.00 | 660.00 |
| Carpet deep clean, waiting room, 17 Oct 2026 | 1 | 240.00 | 240.00 |
| Window cleaning, interior and exterior (hours) | 3 | 45.00 | 135.00 |
| Subtotal | 1,035.00 | ||
| Discount (5% loyalty) | −51.75 | ||
| Total due | 983.25 | ||
5% of 1,035.00 is 51.75, leaving 983.25. Tax is left at zero because, in this example, the cleaning company isn't charging sales tax; rules on taxing services vary by state, so check yours. For more completed samples, browse our invoice examples.
Filling out an invoice on paper, in a spreadsheet or online
The boxes are the same everywhere, but each format has its own traps.
- Paper or printed forms. Write in block capitals with a dark pen, calculate each line with a calculator and write the total twice-checked. Keep a carbon copy, a photo or a scan of every invoice you hand over, because once it leaves your hands you have no record. Number paper forms in advance so you can't skip or repeat a number.
- Spreadsheet templates. Type only in the input cells (description, quantity, rate, dates, client) and leave the formula cells alone. After filling it out, check that the subtotal range includes every line you used, then export the invoice area to PDF.
- Online invoice generators. Fill in the form fields and watch the live preview update. The amount column, subtotal, discount, tax and balance due calculate for you, so your main job is checking descriptions, dates and payment details before downloading.
Whichever format you use, fill the invoice out the same way every time. A consistent order (your details, client, number, dates, lines, totals, payment) makes it much harder to forget a box.
What to leave blank (and what never to)
- Fine to leave blank: PO number (if none was issued), discount, shipping, amount paid, signature, logo.
- Never leave blank: invoice number, invoice date, your details, client details, at least one line item, total due, payment instructions.
- Don't invent: a tax ID or tax rate you're not registered for.
- Don't write "N/A" everywhere. Remove or hide unused boxes for a cleaner invoice.
Final check before you send
- Is the invoice number new and next in sequence?
- Does the Bill to name match the contract or PO?
- Is the due date an actual date?
- Do quantity × rate and the totals add up?
- Are payment details complete and correct?
- Does the PDF look right on a phone screen?
Need help with the wording of each section rather than the boxes? Read how to write an invoice. For a walkthrough of every control in our tool, see the invoice generator user guide.
Fill out your invoice online
Filling out an invoice takes minutes once you know what goes in each box. Open the free invoice generator, choose the clean Classic invoice template, fill in the fields above and download your PDF. Billing in the UK? The UK invoice generator pre-sets GBP and VAT fields.
Frequently asked questions
How do you fill out an invoice for the first time?
Start with your business details, then the client's billing details, a unique invoice number, the issue and due dates, each item with quantity and rate, the totals, and your payment instructions. Check the maths and save it as a PDF before sending.
What do I put in the Bill To section of an invoice?
Enter the legal name of the business or person who will pay, their billing address and, if required, their tax ID or PO number. Use the details from your contract or purchase order, not just a contact's name.
What if a field on my invoice template doesn't apply?
Leave optional fields such as PO number, discount or shipping blank or remove them, rather than writing N/A everywhere. Required fields such as invoice number, dates, line items and total due should always be completed.
Do I fill out a tax field if I'm not registered for tax?
No. If you are not registered to collect sales tax, VAT or GST, leave the tax rate at zero and don't show a tax ID you don't have. Check with your tax authority if you're unsure whether you need to register.
Should I fill out an invoice by hand or digitally?
Digitally, in most cases. A typed invoice is easier to read, the totals can be calculated automatically, and a PDF copy is easy to store and resend. Handwritten invoices are acceptable if complete and legible.
How do I fill out quantity and rate for a flat fee?
Enter a quantity of 1 and put the full agreed fee in the rate box, so the amount equals the fee. In the description, name the deliverable and reference the quote or contract, for example Logo design package per quote Q-2026-014. If you bill a flat fee in stages, add the stage, such as 50% on approval of concepts.
How do I fill out hours and minutes on an invoice?
Convert minutes to decimal hours before you enter the quantity: 15 minutes is 0.25, 30 minutes is 0.5 and 45 minutes is 0.75. So 3 hours 45 minutes becomes 3.75, and at 60.00 an hour the amount is 225.00. Use the same rounding rule every time, such as the nearest quarter hour, and agree it with your client.
Which date goes on the invoice, the work date or the day I send it?
The invoice date is the day you issue it. Put the date or period the work was done in the line description, or in a separate service or supply date field if your template has one. In VAT and GST systems the date of supply can affect when tax is due, so show it whenever it differs from the invoice date.
What do I put in the PO number box if the client never gave me one?
Leave it blank, or remove the box, rather than inventing a number or writing N/A. Before sending, it is worth asking the client whether they need a purchase order, because many companies' accounts payable systems reject invoices without one. If they send a PO later, it usually goes on the invoice they will actually pay.
How do I fill out an invoice for expenses or mileage?
Put each expense on its own line, labeled at cost or with any agreed markup, and keep the receipts. For mileage, enter the miles or kilometers as the quantity and your agreed per-mile rate as the rate. Government mileage rates, such as the IRS standard rate, are for tax purposes and don't set what you can bill, so agree a rate first.
Invoice Creator Editorial Team
Guides on invoicing, cash flow and small-business finance from Invoice Creator, operated by Next Software Development Company. Content is reviewed for accuracy against the fields our own invoice generator produces.
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