If I have to pay my taxes late...

[WhoIam]

I'm about halfway through doing my taxes/determining my net income, and so far it looks like the amount I owe will be less than expected. If for some reason, it ends up being more, there is a real chance I won't be able to pay the full amount by April 15th. If this is the case, how should I handle this, and what can I expect to pay in terms of penalties. I would be able to pay maybe 80% of what I owe on time and the rest a month or two late.