re: Steps for paying uncle sam in advance of tax return filing

Directly from the IRS:

When to pay estimated taxes

For estimated tax purposes, a year has four payment periods. Taxpayers must make a payment each quarter. For most people, the due date for the first quarterly payment is April 15. The next payments are due June 15 and Sept. 15, with the last quarter’s payment due on Jan. 15 of the following year. If these dates fall on a weekend or holiday, the deadline is the next business day.

Farmers, fishermen and people whose income is uneven during the year may have different rules. See Publication 505, Tax Withholding and Estimated Tax, for more information.

If a taxpayer doesn’t pay enough or pays late, a penalty may apply.