Setting up VAT, GST and other types of taxation

Inca Clinic supports the calculation of taxes such as VAT and GST. You just need to enable the feature.

Enabling Tax

The admin page

  • Click on Tax Label / Rates. Note that this has a spanner icon beside it to indicate that it opens a dialog box where you can edit the settings.
  • If you have no tax labels set up, tax will not be enabled in your system. Simply add a label for the tax, and click Save to enable it:

Set your sales tax rates

  • Once you have added a label, you can then set up one or many tax rates. Add the name for the rate, the rate (as a percentage), and click Save:

  • When you have added one or more tax rates you will be able to select the applicable tax rate for each price for a product. If you subsequently change a tax rate this will update all prices with that tax rate.

Rounding Rules When Calculating Sales Tax

Rounding is an envitable consequence of working with percentages. This is recognised by taxation authorities and they provide guidelines on how rounding is to be carried out. Inca Clinic adopts the UK rules (see UK VAT Notice 700: The VAT Guide), but these are similar to the rules in many other countries

The product prices that are entered into Inca Clinic price books are tax-inclusive. For example, the sales-tax-incluxive price for “Aloe Gel” is shown here to be 15.50:

Entering a price for a product.

The Show pre-VAT price button allows you to see the sales tax calculation for that individual product.

Showing the pre-VAT price.

However, as will be explained later, the tax on each individual product is treated slightly differently when they are part of a multi-product invoice.

Sales Tax in Invoices

An invoice is generated either via the Waiting Room or via a Patient Record page.

Here's a sample invoice (the sales tax is called GST in this example):

Sample invoice showing sales tax.

Details on how the sales tax is calculated

All of the prices and tax are shown in the invoice to two decimal places (e.g., tax of 16.65). However, internally within Inca Clinic the tax calculations are done to 3 decimal places.

Here's the internal calculation for the above invoice:


  • Column “I” shows the VAT to 3 decimal places. Figures are rounded down to 3 decimal places to create the entries in this column.
  • Cell “I10” (value 19.826) is the total VAT, again to 3 decimal places.
  • This value is rounded down to 2 decimal places to give the final VAT of 19.82 (cell “I11”). (It would not have been correct to round down the individual line items to 2 decimal places; but it is correct to round down the total tax value to 2 decimal places.)


Internally in Inca Clinic, to ensure that the final tax calculations are correct, line items are stored to 3 decimal places. However, as is normal for invoices, line items are displayed rounded to 2 decimal places, and therefore occasionally there may seem to be rounding anomalies in the printed invoices. Even where these do arise, the all important final tax amount will be correct. If required, you can run a report that shows a full 3 decimal place analysis of invoice line items. If you wish to have invoice line items displayed to 3 decimal points or have an analysis report created, please contact

Extract from the UK VAT rules

17.5.1 Calculation based on lines of goods or services. Where VAT is calculated separately for a line of goods or services, which are included with other goods or services in the same invoice, you should calculate the separate amounts of VAT either by rounding:

  1. down to the nearest 0.1p – for example, 86.76p would be rounded down to 86.7p,
  2. or, to the nearest 1p or 0.5p – for example, 86.76p would be rounded up to 87p

Whichever option is chosen must be consistently used in all calculations.

The final total amount of VAT payable may be rounded down to the nearest whole penny.

(Inca Clinic adopts the first of the two choices above.)

Making additional fields appear on the Invoice PDF

This is planned for a future release

Inca Clinic uses what are known as Field Sets to allow you to configure what appears on an Invoice PDF. Field Sets allow you to optionally include certain fields on standard pages and pdf pages. To add/remove fields from the Invoice PDF, you should do the following:

  • Login as an Administrator.
  • Find the Field Set that you want to edit by going to Your NameSetupView Installed Packages, clicking on the Inca Clinic installed package, and then clicking on the Invoice Line Items Fields Set.
  • To move fields between the lists: highlight a field and click the appropriate left or right arrows. To change the order of a rendered field, highlight the field and click the up or down arrows.
  • Click Save.
tax.txt · Last modified: 2014/12/10 11:40 by richard
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