You can. All of these options can be found by clicking on the Settings link at the top of the page. Then, hit the Invoice Details button in the sidebar on the right.
For late fees, select one of four options from the Late Fees pulldown menu: No late fee, 1% per month, 1.5% per month or 2% per month.
Check the Sales Tax box if you want sales tax applied by default on every invoice. (Late fee and sales tax options can also be changed on each invoice, regardless of the defaults.)
If you need to use a different sales tax rate, click on the Change this link and type in a new percentage.
If you need to support a tax system other than that used in the US, the Tax Name and Tax ID options are for you. Tax Name is what you call the tax in the system you’re using — “sales tax,” “VAT,” “because-I-feel-like-it tax,” etc. Tax ID is the number that identifies you to the government body collecting those taxes. If you don’t know whether you need one, it’s probably okay to leave it blank.
(Note: Blinksale, Inc. will not be responsible for you getting thrown in debtor’s prison. But if that happens, write us and we’ll see about comping your account.)
Hit the Save Settings button at the bottom of the page when you’re done.