Expect to owe the city more than $200 for the year and you declare an estimate and pay it in four parts - April 15, June 15, September 15 and January 15 - each at least 25% of what you declared. Together they need to reach 90% of this year's tax or 100% of last year's, or penalty and interest follow. No extension of time to pay is granted.
A resident pays the city's rate - Columbus 2.5% - on all income: wages and the net profit of a sole proprietorship, wherever earned. A business loss is entered as zero and never set against wages, but it carries forward against later profit. Tax paid to the city where you worked is credited, 100% up to 2.5% of that income. A return is due even in a loss year, by April 15; a balance of $10 or less needs no payment.