If my plus account max provides 5 users free, what is the cost of an additional user?

I've got an option for you, colleen-chan.

QuickBooks Online Plus version includes 5 billable users + 2 accountant users. If you're at your plan's user limit and need to add new users, you can either do the following:

• Manage existing users
• Upgrade to a different plan. Note: You can see upgrade option if you have the Simple Start or Essentials plan.

Since you already have the Plus version, I'd recommend removing a user that no longer needs access. Then, add the new one by following these steps:

1. Go to the Gear > Manage users.
2. In the Manage users page, find the user you want to remove.
3. Click the arrow beside Edit and choose Delete.
4. Select Delete to confirm.

Here's a sample screenshot for a visual guide:

Once done, click the Add user button and enter the user's information. You can check out this article to learn more: Add, delete, or edit a user.

Tip: Some user types like reports only and time tracking only don't count toward the user limit. Make sure each user in QuickBooks has the access that's right for them.

I'm also adding these article that you can use as a guide:

• How many users can I set up?
• Add and manage users in QuickBooks Online
• User types and user permissions in QuickBooks Online

If there's anything else you need with QuickBooks, please add it in your reply below. I'll be glad to answer them. Take care and stay safe.

@colleen-chan 

QBO Plus provides 5 users seat. Consider having a 3rd party app as a workaround to integrate with your QBO account. e.g You may ask your sales team to use a CRM app and they don't need to access QBO. 

Hi, thanks for your answer. However, I'm on Plus and I clicked to Upgrade but I could not?

See screenshot below.

Hello again, colleen-chan.

I'd like to clear things up. The steps regarding the upgrade that I've provided previously will only apply if you are subscribed to the Simple Start or Essentials plan.

I have updated my answer above. Since you already have the Plus version, you'll want to remove a user and add the new one or follow the suggestion provided by Fiat Lux - ASIA.

Please feel free to get back to me if you have any follow-up questions or other concerns. Thanks.