You can enter your own amount for a provision tax period rather than using Solo's calculated amount. This can be helpful if you have started using Solo part-way through the financial year and you have already paid some provisional tax. Or if you would simple prefer to use the IRD's estimated provisional tax amount instead of the amount that Solo has calculated based on your income and expenses.
To enter a custom provisional tax amount:
Go to the Taxes page in the main navigation.
Click on the Pay button next to the Provisional tax period you want to adjust (the period must be due for the button to be visible).
Click the link I paid a different amount at the bottom of the page that pops up.
Enter the amount that you paid.
Click Done.
The entered amount will then be used when calculating future provisional tax and income tax.