The article says:

Kra gives landlords march deadline

"...For instance, a tenant with 10 housing units at a monthly rent of Sh10,000 is expected to pay Sh12,000 in taxes a year but the amount could be lower if some units are not occupied..."

Is this correct? Do they mean 120,000 in taxes a year? (12,000 a month)?

10 units X 10,000 per month = 100,000
100,000 * 12 months = 1.2 million
Annual tax due (10% * 1.2 million) = 120,000 (tax rate is assumed to be 10%)

No ,10 units at 10,000 a unit gives you a total of 10x10,000 =100,000 for the whole 10 units per month

Now tax is (12/100)X100,000= 12,000 tax per month for all the 10 units

Every year it will be 12×12,000 =144,000 against a total revenue of 1,200,000