Why is my client's Sales Tax different than my purchase Sales Tax?

Purchasing and selling items in different tax locations can cause different tax amounts on the purchase and selling side of your items.

Client Sales Tax

In Studio Designer the client sales tax is based off of the tax location set for the client, this is because most tax laws require that the client is charged sales tax based on where they are located.
You can review the tax location on a client by going to Projects > Clients and checking the Codes tab.
Any client sales tax on an item will be calculated based off this Tax Location

Purchase Sales Tax

If you want to record sales tax that you paid while purchasing the item, you will have to enter that manually on the Purchase Cost section. Note: This is not tied to the selling sales tax and will not copy over to the selling side. This is because the client's sales tax is calculated based on the client's Tax Location, as mentioned above.

Difference in Sales Tax

Sometimes the sales tax you paid when you purchased the item can be different than the sales tax you are charging the client. This happens when you purchase the item in a different tax location than the client's tax location. (For example: If you purchase an item in New York, but sell to a client with a Florida tax location, the sales tax rate is different for those two locations. So the purchase sales tax and the selling sales tax will be different. )
If there is a difference between how much sales tax you were charged and how much the client was charged, you should consult with a tax accountant on if you are allowed to pass that additional sales tax on to the client or not. This is because there may be certain tax laws that prohibit you from charging additional sales tax to your clients.
If you consult with a tax advisor on these situations and determine that you can charge the difference in sales tax to your client, you can include additional sales tax by either adjusting the selling price of the item or adding it as an Other Cost.