Generally, taxpayers who are self-employed, are shareholders in S-Corporations that typically pay out distributions in addition to the wages paid to the owners, partners in profitable partnerships, and/or report a good amount of investment income should consider paying in estimated taxes during the year.
The IRS now recommends that individuals make their estimated tax payments electronically. Read more at: National Small Business Week: Making estimated tax payments electronically is fast and easy | Internal Revenue Service (irs.gov).
To pay your estimated taxes electronically, go to www.irs.gov, click on Make a Payment and then click on Pay Now with Direct Debit. Follow the prompts and make the payment by direct debit from your bank account. Other options are available to pay your estimated taxes including how pay them by credit card and the associated fees to do so.