What is a duplicate invoice book?
Duplicate books are the most common business book we print. Most tradespeople, garages, shops and small firms in Ireland use one, because two copies cover what they need: one to hand over and one to keep.
How a duplicate invoice book works
Each set in the book has two sheets of carbonless paper. The back of the top sheet is coated with tiny ink capsules. The front of the bottom sheet has a coating that reacts with that ink. Pen pressure bursts the capsules and the copy appears. If you want the detail, How does NCR paper work, and is it the same as carbonless or thermal paper? explains it.
A good duplicate book also has:
- A cover and a stiff back, so you have something firm to write against.
- A writing shield, a card you slide under the set you are using so the pressure does not mark the sets below.
- Perforation, so the top copy tears out cleanly while the second copy stays bound.
- Sequential numbering, printed on both parts of every set.
How many invoices are in a duplicate book?
There is no standard. Many suppliers bind 50 sets in a duplicate book, and off-the-shelf books from office suppliers often hold 50 or 100. Our duplicate books hold 100 sets, which is 200 sheets. That means one book lasts twice as long between orders as a 50-set book, and the cost per invoice is lower.
To work out how many books you need for a year, multiply the invoices you write per week by 52 and divide by the number of sets in a book. We explain the sums, and when it pays to order more, in How many invoice books will you need in a year?
Which size should you choose?
| Size | Dimensions | Best for |
|---|---|---|
| A4 | 210mm x 297mm | Itemised invoices with a dozen or more lines, such as garages, builders' suppliers and engineering firms |
| A5 | 148mm x 210mm | Six to ten lines and a total. The size most trades keep in the van |
| A6 | 105mm x 148mm | Pocket-sized receipts and cash sales written on the spot |
| DL | 99mm x 210mm | A tall, narrow slip for one or two lines and a total, which posts in a DL envelope without folding |
If you are torn between A5 and A4, look at your last twenty invoices. If most have more than ten lines, choose A4. Our earlier article When A4 is the right size for a duplicate invoice book covers that decision.
Duplicate or triplicate?
Choose duplicate unless a third copy genuinely has somewhere to go, such as an office, a driver or a separate job file. A triplicate book has fewer sets per book and costs more per invoice, and an unused third copy is paper you pay for and store. What is the difference between duplicate and triplicate? walks through who needs three copies.
Off-the-shelf or personalised?
Generic duplicate books from stationery shops are cheap per book, but every invoice needs your business name, address, phone number and VAT number written by hand, and the numbering starts at 1 in every book. That creates duplicate numbers across books, which is a problem for VAT invoices, because Revenue requires a unique sequential number on each one.
A personalised book prints the details that never change, continues your numbering from the last book, and looks more professional to the customer. For most businesses writing more than a few invoices a week, the time saved pays for the difference.
What to check before you order
- Sets per book. 50 or 100 makes a big difference to the real price per invoice.
- Numbering. Is it included, is it printed on both parts, and can it continue from your last book?
- Perforation edge. Top or left, depending on how you hold the book.
- Writing shield and backing board. Without them you get ghost marks on unused sets.
- A proof. Check spelling, VAT number and bank details before anything is printed.
Duplicate invoice books with 100 sets, printed in Ireland
Discoverprint's duplicate invoice books hold 100 numbered sets (200 sheets) in A4, A5, A6 or DL, perforated at the top or the left, with a manilla cover, cardboard back and wrap-around writing shield. The number is printed on both parts of every set and numbering is included in the price. Design is free, a proof is emailed within one working day, books are dispatched 3 to 4 working days after approval and delivery is free anywhere in Ireland, north and south. See the full NCR books range.
Read next
Frequently asked questions
- What is a duplicate invoice book?
- A book of numbered two-part carbonless invoice sets. When you write on the top copy, the writing transfers to the copy beneath. The customer takes the top copy and the second copy stays in the book as your record.
- How many invoices are in a duplicate book?
- It depends on the supplier. Many bind 50 sets per book. Discoverprint's duplicate books hold 100 sets, which is 200 sheets.
- What is the difference between duplicate and triplicate?
- A duplicate set has two parts, an original and one copy. A triplicate set has three, an original and two copies, for when a third person needs the paperwork.
- Are duplicate invoice books numbered?
- Printed books usually are. At Discoverprint the number is printed on both parts of every set, so the customer's copy and yours always match, and numbering is included in the price.
Sources
- Revenue: What information is required on a VAT invoice?
