If you have bought or sold investments or especially if you are a business owner, Tax Planning will provide you an estimate of the taxes and a plan to pay before you file. No surprises.
The IRS assesses several penalties and accrues interest on any debt. Underpayment penalty, Failure to pay and Failure to File are just a few.
The easiest way is depending on the amount, file form 9465 for an Installment Agreement.