> For the complete documentation index, see [llms.txt](https://www.zerabooks.com/help/llms.txt).
# Create an invoice
Build an invoice from scratch: choose the customer, add line items, set the dates and discounts, then preview it before you approve.
## Start a draft
1. Go to **Bills & Invoices** › **Invoices**.
2. Click **Create Invoice**. ZeraBooks creates a draft dated today and opens it.
Nothing is in your books yet. A draft only posts when you approve it.
## Fill in the invoice
1. **Customer:** click it and pick a customer. Type to **Filter by name or email**, or choose **Add Customer** to create one on the spot.
2. **Invoice Number:** ZeraBooks fills in the next number. You can type your own.
3. **Reference Number** (optional): a purchase order or job number, for example `PO #1234`.
4. **Invoice Date** and **Due Date:** the due date picker offers terms: **Upon receipt**, **15 days**, **30 days**, **45 days**, **60 days** or **90 days**. Changing the invoice date moves the due date with it.
5. For each line, fill in **Item**, **Qty** and **Price**. Picking a product or service from your catalog fills in its price and category. **Total** is calculated as quantity × price.
6. Choose a **Category** for every line: the income category the sale posts to. **Select or Create New** lets you add one without leaving the invoice.
7. Click **Add Line Item** for more lines. **Add Description** adds a second line of detail under an item.
8. To give a discount, click **Add Discount** and pick one, or choose **Add New Discount** to create it (a **Percent** or **Fixed Amount**).
{% hint style="info" %}
**Tip:** The **Tax** field on each line appears once you've declared a sales tax account, and **Retainage / holdback** appears once you've declared a holdback account. Both are set in [Invoice accounting settings](https://www.zerabooks.com/help/invoices/invoice-accounting-settings).
{% endhint %}
## Add a message and branding
The panel on the right has **Branding** (a colour or cover image) and **Memo**, the message shown on the invoice. See [Invoice branding](https://www.zerabooks.com/help/invoices/invoice-branding).
## Preview and approve
1. Click **Save & Preview** (or **Preview**) to see the invoice as your customer will.
2. Click **Approve** to post it, or open the arrow next to it for **Approve & Close**. See [Approve an invoice](https://www.zerabooks.com/help/invoices/approve-an-invoice).
To stop for now, open **More Actions** (the three dots) and choose **Save Draft** or **Save Draft & Close**.
If **Preview** is unavailable, hover over it to see what's missing. ZeraBooks checks the same things when you save:
| Message | What to do |
| --- | --- |
| "Choose a customer before saving." | Pick a customer. |
| "Choose a due date on or after the invoice date before saving." | Move the due date. |
| "Add at least one line item." | Add a line. |
| "Replace Uncategorized Income on line N before saving." | Pick a specific income category for that line. |
| "Invoice date is in a closed period" | The books are closed through a later date. Use a date after it, or reopen the books. |
| "Quantities can’t be negative. For a credit, keep the quantity and enter a negative price." | Make the price negative instead. See [Credit memos](https://www.zerabooks.com/help/invoices/credit-memos). |
## Frequently Asked Questions
Can I change the invoice number?
Yes. Type over it in **Invoice Number**. Otherwise ZeraBooks numbers invoices `INV--0001`, `INV--0002` and so on by invoice-date year, or continues your own series (for example INV-1008 → INV-1009) if you never used the year series. A number that was assigned once is never reused, even if you delete that draft.
What payment terms are available?
**Upon receipt**, **15 days**, **30 days**, **45 days**, **60 days** and **90 days**. You can also pick any due date on the calendar, as long as it's on or after the invoice date.
Can I put invoice lines in different income categories?
Yes. Every line has its own **Category**, and the approved entry credits each category with its own line.
Can I create a product or a discount while building an invoice?
Yes. A line's category picker offers **Select or Create New**, and the discount picker offers **Add New Discount**. A new discount posts to a Sales Discounts & Allowances category; if you have none, ZeraBooks says "Declare a Sales Discounts & Allowances category before applying this discount."
Does ZeraBooks calculate sales tax for me?
No. Enter the tax amount on each line. The **Tax** field appears once a "Tax charged on sales" account is declared in [Invoice accounting settings](https://www.zerabooks.com/help/invoices/invoice-accounting-settings).
Can I create recurring invoices or estimates?
No. ZeraBooks has no recurring invoices or estimates. To reuse an invoice, open it and choose **Duplicate**, which makes a new draft with the same lines.
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