From 1st Jan 2019, Microsoft are increasing the pricing of Office 365 subscriptions by up to 8% in order to bring them in-line with pricing in other regions. The last price adjustment for Office 365 was more than 3 years ago and it affects all new subscriptions and all renewing subscriptions going forwards.
Office 365 Business Essentials is increasing in price from $84 per person per year to $91 per person per year. Office 365 Business Premium is increasing from $210 per person per year to $229 per person per year.
If you have a current subscription and wish to add more seats to the tenancy, these new seats will be billed at the previous price up until your subscription renews, at which point it will switch to the new pricing.