For business planning purposes, we recommend a very simple approach to estimating corporate and sales taxes. LivePlan uses a single flat percentage to calculate each of these.
If you're outside the U.S., you may need to represent a more complex sales tax system, such as the VAT, HST, or GST in your forecast. LivePlan isn't able to track the tax payments and credits involved in these types of taxes in detail, but you can use the flat-percentage model to get a reasonable estimate of your taxes for forecasting.
To represent sales tax credits, or taxes paid on expenses, we normally recommend determining the difference between taxes paid and tax credits, and using that as your flat sales tax percentage in LivePlan. So, for example, if you normally charge 25% VAT/HST/GST but get a 5% tax credit credit, the cumulative difference is 20%. Using that 20% as your sales tax setting in LivePlan should get you a close estimate of your tax liability.
If you require a more detailed handling of sales tax payments and credits, we do have a Windows desktop product that is specifically designed for this. Business Plan Pro UK edition includes a very detailed VAT/HST/GST Handling utility that will help you to forecast Input and Output, Payments and Credits if that is what you need.