Sales Invoice Lines

An invoice has two parts. The header says who and when — the customer, the dates, the company raising it. The lines say what — each line is one thing you're billing for: a product or service, how many, at what price. The lines are where the money actually comes from; the invoice total is simply the sum of its lines. This article explains every field on a line, how REDA works out the line's amount and tax, and the few rules that keep your lines clean. No accounting background is assumed.

What's on a line

You fill in only the first few fields — pick a product, set a quantity — and REDA derives the rest. Here are the fields you'll work with on a line and where each comes from:

How a line's amount is worked out

Each line produces two figures, both calculated for you and never typed by hand:

• Line Amount — the net figure, before tax. In the normal case this is simply Quantity × Unit Price − Discount.
• Total — the gross figure: Line Amount + Tax.

The Line Amount is the number that matters most: it's what feeds the invoice's Subtotal, it's the base the tax is calculated on, and it's what gets booked to your revenue account when the invoice posts. A quick worked example — ten hours of consulting at £100, with 20% VAT:

These figures update live as you type — change the quantity, the price or the discount and the line re-totals instantly, with the tax recalculated by the engine.

Tax on top, or tax already in the price?

Every line has a Tax Base setting with three choices. The first two answer one question — is the price you entered before tax, or does it already include tax? — and the third switches tax off for the line altogether:

Most businesses bill exclusive of tax (the default). Inclusive is common in retail and some countries, where the shelf price already contains the tax. The same £120 entered each way shows the difference, at 20% tax:

Discounts on a line

The Discount field takes a money amount off a single line — for example £150 off, not "15%". REDA subtracts it before working out the tax, so a discount reduces both the revenue and the tax. Ten hours at £100 with a £150 discount, 20% VAT:

Credit lines: the Income / Credit toggle

Each line has a small toggle that marks it as either Income (the normal case — you're billing the customer) or Credit (you're giving money back). A line switched to Credit simply flips its sign: instead of adding to what the customer owes, it reduces it. A £100 credit line contributes −£100 to the invoice.

You'll meet this mainly on a Credit Memo — a document whose whole purpose is to give the customer credit, so its lines are credit lines. On a normal invoice the toggle stays on Income, which is the default — though you can flip a single line to Credit for a small adjustment alongside new charges, as long as the invoice total stays positive. The form shows a small Income or Credit badge on each line so the sign is never ambiguous.

The revenue account on a line

Every line books to a GL Account — the revenue account that records the income from this sale (for example "Consulting Revenue" or "Product Sales"). You rarely set it by hand: choosing the product fills it in from the product's default revenue account. You can override it on a line when a particular sale belongs to a different account.

Because the GL Account decides where your revenue lands, REDA checks the one you choose. It must be an active account, it must be in scope for the invoice's Entity, and its territory must match the invoice — guards that stop revenue being booked to the wrong or a retired account. If a choice is invalid, you're told at once rather than at posting time.

Configurable fields on a line

A Sales Invoice line carries the same two configurable field lists as the header — named lists of fields an administrator can change without code:

• On-screen field list (line) — the extra columns the form shows on each line. The standard columns (Product, Description, Quantity, Unit Price, Line Amount, Tax Profile, Tax Amount, Total, GL Account) are always there; out of the box the list adds a Cost Center column. Add a field here — say a project code per line — and it appears on every line automatically.
• Posting map (line) — the line fields copied onto the accounting entries when the invoice posts. Out of the box it carries Cost Center, so each line's cost center reaches the ledger.

Your accounting dimensions (Cost Center, Project, Property…) can therefore be set at the header — flowing to the accounting entries for the whole document — or per line, where a line's own value overrides the header's for that line's entries. For the full picture of these field lists, see Understanding the Sales Invoice.

Source Line Taxes: the tax audit trail

When the tax engine works out the tax on a line, it doesn't just stamp a number on the line — it writes a Source Line Tax record: a permanent, itemised record of one tax, on one line. You never create or edit these yourself. They are written when the invoice is posted — while it's still a Draft, the form shows you a live preview of the tax, but the Source Line Tax records themselves are created at posting. They are what make your tax fully auditable — every penny of tax can be traced back to the line, the rate and the rule that produced it.

Each Source Line Tax record captures:

A worked invoice: three lines, their taxes, the totals

Let's put the whole chain together on one real invoice — from Meridian Properties UK Ltd, billed in GBP, exclusive of tax, with three lines:

Each Line Amount is just Quantity × Unit Price − Discount — line 2 is 2 × £800 − £100 = £1,500. When you post, the tax engine writes one Source Line Tax per line (you see the very same figures as a live preview while the invoice is still a Draft) — here all standard-rate 20% VAT:

And then every total builds itself, bottom-up — nothing is added by hand:

Always edit lines from the invoice

A line is part of an invoice, not a standalone record — so always add, change or remove lines through the Sales Invoice form, never by opening a line on its own and editing it directly. There are two solid reasons.

First, the form is the supported, safe way to work: it validates the whole document as you build it — line by line — and shows the live tax and the running totals, so you always see exactly what the invoice will post as. Editing a raw line record on its own skips that guided experience and the live preview.

Second — and this is the firm one — once an invoice is posted, its lines are locked: REDA blocks direct line edits outright. You never tinker with a posted line. To change a posted invoice you reopen or void it from the invoice itself (see Editing, unposting and voiding), fix the lines on the reopened Draft, and post again — at which point the tax is recalculated fresh.

Common mistakes to avoid

A few traps catch people new to REDA. Each is easy to sidestep once you know it:

The rules that keep lines clean

A handful of checks run as you build a line, so a flawed line can never reach your books. Each one surfaces immediately with a plain-language message:

Where to go next

1. Creating a Sales Invoice — start a new invoice.
2. Tax on Sales Invoices — how line tax is calculated.
3. Posting a Sales Invoice — post the invoice.
4. Creating Products — products drive line defaults.

Frequently asked questions