Do I owe taxes for an ongoing agreement?
As best I understand the tax laws, you do not owe any tax on money you have not received. If you have received some money but not all then you can classify it as an installment sale. However that makes it complicated to figure out if there was a capital gain or not and what part of the money received was an actual gain. You could make the argument that the capital gains are not realized until the entire amount is paid.