If we upgrade our plan from Starter to Plus will it affect the period of our subscription because our current plan will be due on January 2020

We are thrill with upgrading your subscription, cremasharon.

No, it will not affect the period of your subscription when upgrading to QuickBooks Online (QBO) Plus. Your subscription period will be based on when you purchased or subscribed the product. Also, the current rate depends on its original rate and any discounts offered at the time your subscription began.

Here's how you can upgrade your QBO subscription:

1. Click the Gear icon on the top menu.
2. Choose Account and Settings.
3. Choose Billing & Subscription menu.
4. In the QuickBooks Online section, click Upgrade. If you don't see it, you’re already using the plan with the most features.
5. Choose the plan you want, and click Upgrade.
6. Confirm your payment information and click Save.

For more details about understanding your subscription rate, you can check out this article: https://community.intuit.com/articles/1775286.

You can also check out the Billing Hub for Small Businesses article to learn more about managing your Online account.

Just add a comment below if you need anything else with QBO subscription. I'm always here to help.