If a template contains conditional text that shows or hides depending on the taxpayer's situation, it is not easy to predict where a page break will appear. However, you can control pagination so that page breaks only occur where you want them to.
There is no way to insert or remove a page break from a letter in the Template Editor. However, adjusting Paragraph properties can help you control where page breaks appear.
You can turn these options on to force the behaviour, or you may find some of our built-in templates already have them enabled, so disabling the option could be what is needed.