The Tool Desk
Outbyte Driver Updater FREEFix the driver behind crashes, sound loss and screen glitchesFind Drivers →Outbyte PC Repair FREEClear out junk files and repair common Windows errorsFree Scan →To find the tax already included in an invoice total, multiply the total by the tax rate and divide by 1 plus that rate. For a rate written as a percentage, use included tax = total × rate ÷ (100 + rate). The amount before tax is the total minus the included tax. This works when the amount is genuinely tax-inclusive and all of it has the same tax treatment.
Use the tax-inclusive formula
Let G represent the gross total (the amount including tax) and r represent the rate as a decimal:
- Included tax: G × r ÷ (1 + r)
- Pre-tax amount: G ÷ (1 + r)
If the rate is written as a percentage p, use:
- Included tax: G × p ÷ (100 + p)
- Pre-tax amount: G × 100 ÷ (100 + p)
These are equivalent ways to separate the tax and taxable amount from a tax-inclusive price. The Finnish Tax Administration publishes this calculation for VAT-inclusive amounts: VAT calculator.
Why you do not multiply the total by the stated rate
The tax rate is applied to the pre-tax amount, not to the tax-inclusive total. At a 20% rate, for example, a pre-tax amount of £100 produces £20 tax and a £120 inclusive total. The tax is therefore 20/120 of the gross amount—one-sixth—not 20% of it. HMRC’s VAT guidance uses the one-sixth fraction for a standard-rated 20% inclusive amount: VAT Notice 700.
#1 Best Overall
- Two-Part Carbonless Invoice Book: Each invoice book has 50 sets of invoices, each with a white/light yellow section, with the yellow section retained in the invoice book to maintain detailed records.
- Consecutively Numbered: Enlarged red 6-digit numbers in the upper right corner of each invoice receipt book help you quickly navigate through your orders.
- Wraparound Divider Flap: A thick folded cardboard divider is integrated into the back of each invoice book for use between each two-part sales order to prevent the written content from rubbing off on subsequent copies of the invoice, resulting in wasted invoices.
- 2 Packs/50 Sets (100 Sets Total): Each invoice book provides 50 sequentially numbered carbonless sets of 2 invoice books for long-term use.
- Customizable Space: Each invoice book for small business has space at the top to add a company seal or sticker.
Worked calculations
$109 total at an illustrative 9% rate
Using 9% as the illustrative rate in Singapore IRAS guidance, included tax is $109 × 9 ÷ 109 = $9, leaving a pre-tax amount of $100. The rate is an example, not a claim that every Singapore transaction uses that treatment. IRAS guidance on absorbing GST.
£120 total at the UK standard-rate example of 20%
At 20%, £120 ÷ 1.20 = £100 before VAT, so the included VAT is £20. HMRC also shows the reverse calculation: £60 excluding 20% VAT becomes £72 including VAT. Its guidance lists UK standard VAT as 20% and reduced VAT as 5%; these are UK rates, can change, and do not establish the treatment of every supply. HMRC VAT rates and VAT Notice 700.
Rank #2
- PACKAGE INCLUDES - Our invoice book per pack has 50 sets sheets, Total of 100 sheets. red code printed on each page with consecutive numbers
- Material - Receipt book is excellent quality carbonless paper is used in their production, tears off easily along the perforation.
- A5 Size - Sales invoice book size of 5.5" x 8.5", and forms are 2 part carbonless white/yellow sets on a sturdy chipboard backing
- WIDE APPLICATION - Sales reciepts/invoice book for small business is ideal for restaurants, food trucks, vendors, service provider, photographers, caterers, florists, bakeries, cafes, boutiques and salons
Authority examples in other currencies
The Finnish Tax Administration’s example, on a page updated 2026-01-01, separates €148.09 inclusive of 25.5% VAT into €30.09 VAT and a €118.00 taxable amount. Singapore IRAS gives a $10,000 amount inclusive of 9% GST, producing $825.69 GST and a $9,174.31 supply value. These are examples from the authorities, not default rates or treatments for other transactions. Finnish VAT calculator; IRAS absorbing GST.
Check the invoice before calculating
- Identify the applicable jurisdiction, transaction date, supply type, and rate. Tax rates and treatments vary, and an authority may change a rate from an effective date. Check current official guidance rather than relying on an old example; HMRC notes that UK VAT rates can change. HMRC VAT rates.
- Confirm that the stated total includes tax. If tax is added on top of an exclusive price, calculate tax on that pre-tax base instead; do not use the inclusive formula.
- Apply the formula only to a single-treatment amount. If all relevant lines have the same rate and treatment, calculate from their tax-inclusive total.
- Separate mixed supplies. If the invoice has different rates, exempt items, or zero-rated items, calculate by category or use a locally accepted apportionment method. HMRC Notice 700 describes apportionment for a mixed zero-rated and standard-rated inclusive price. VAT Notice 700.
- Round using the local method at the required level. Rounding each line or unit before adding can differ slightly from calculating once on the invoice total. Finnish guidance says VAT amounts must be expressed to two decimal places; HMRC describes line-level methods and says to use them consistently. Finnish VAT calculator; VAT Notice 700.
Separate the calculation from invoice disclosure
A tax-inclusive customer price does not necessarily remove the seller’s obligation to show tax information separately. Requirements depend on the jurisdiction and invoice type, so the calculation alone is not a complete invoice-compliance check.
What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
Rank #3
- QUALITY INVOICES: Adams Order books provide a professional invoice or customer receipt; a great way to create and maintain a professional image for small businesses and service providers
- 50 TWO-PART CARBONLESS FORMS: Customers get the perforated white top copy; retain the canary and pink copies for your records
- WRAP-AROUND COVER: Fold the back cover between sets to keep invoices neat and legible
- ROOM FOR CUSTOMIZATION: A blank space at top leaves room for your company stamp; a big savings over custom-printed forms
- CONSECUTIVELY NUMBERED: Large 6-digit numbers in the upper right hand corner help you thumb through orders quickly
- United Kingdom: HMRC guidance says invoices must include the VAT number and display VAT separately. Notice 700 covers full and simplified invoice information, including handling for zero-rated or exempt supplies. VAT Notice 700.
- Singapore: IRAS says a tax invoice should show GST as a separate amount. Its guidance also gives inclusive-price wording for certain receipts or simplified tax invoices. IRAS guidance on absorbing GST.
- United Arab Emirates: A 2022 Federal Tax Authority guide lists invoice particulars including the description, unit price, quantity or volume, VAT rate and amount, and total payable. Its AED 220 example calculates AED 10.48 VAT; because the guide is dated 2022, check current UAE guidance before relying on it for a current rate. FTA Tax Invoices Guide.
These country examples are not a universal invoice template. Confirm current rules with the relevant tax authority for the transaction.
Quick Recap
Best Value
- 6-PACK/50 Sets (300 Total Sets): Six 5-7/16 x 8-7/16" bound Sales Order Books with two-part forms which produces two identical records of each sales transaction, one for the customer and one for your business
- CARBONLESS COPY: No carbon paper! Each 2-part set features a white top sheet for recording each transaction and a bottom canary yellow sheet that captures written text from top sheet.
- CONSECUTIVE NUMBERS: Effortlessly identify the chronological order of transactions in each book by the pre-printed number on each sales order set
- WRAPAROUND DIVIDER FLAP: A thick, folded paperboard divider is integrated into the back of each book to use between each 2-part sales order form.
- PERSONALIZE: Each sales order form sheet contains space at the top to add a company stamp or sticker
Rank #4
- Long-lasting utility: 100 sheets per book, offering a total of 400 sets for extended use, Size 7-5/8" x 11".
- Two-Part Carbonless Copy: Achieve clean and legible copies for your records with the carbonless copy paper, making organization a breeze.
- Spiral Bound Design: Convenient and user-friendly, the spiral binding allows for easy flipping and writing, ensuring a seamless record-keeping experience.
- Ample Space: Each page accommodates 4 receipts, providing plenty of room to note down detailed information for each transaction.
- Professional-Grade: Ideal for landlords, businesses, and individuals, this receipt book is a reliable and professional tool for tracking financial transactions accurately.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
