Taxpayers now rushing to meet the Friday deadline for filing 1982 returns should remember to do these three things:

* Check to see if you are eligible for the deduction for a married couple when both work--also known as the marriage tax deduction. Early surveys by the Internal Revenue Service indicate that 10 to 15 percent of those who appeared to be eligible for the marriage tax deduction didn't take it. That means they lost out on a deduction from gross income of as much as $1,500.

* Review your tax status to see if you would benefit by opening an Individual Retirement Account. You can open one as late as Friday and still take the deduction on your 1982 income tax return. For someone in a 50 percent tax bracket, the IRA can reduce taxes by $1,000.

* After completing your return, go back through it for errors. And then, if there is time, have someone else check your forms. This is especially important now because taxpayers filing at the last minute tend to make more mistakes than those who file early, according to IRS.

"The late returns always have a higher error rate . . . probably because taxpayers rushing to meet the deadline are more prone to make mistakes," said IRS representative Rod Young.

The most prevalent error on the long form, Young said, is in the calculation of the medical deduction. The second most common mistake involves the child care credit and the third concerns the tax table.

"People misread the table and pick up the wrong tax," he said.

After that come errors in computing the amount of unemployment compensation subject to tax, in figuring the earned income credit or in trying to take the credit when the taxpayer doesn't qualify, in computing the refund, in taking itemized deductions, in adding up income amounts, in failing to take the earned income credit and in using the wrong standard deduction.

Short form errors, Young said, most typically involve the earned income credit, the wrong tax from the tables, the refund or balance due, the unemployment compensation and charitable contributions.

For those who do blunder, here is some consolation: The chance of having the individual return audited has been dropping in recent years. The IRS now projects that 1.47 percent of the returns filed during calendar year 1982 will be examined, compared to 1.55 percent of calendar year 1981 and 1.77 percent of calendar year 1980.

Those who need tax forms or tax assistance on their federal returns will have to go for them during regular office hours, because IRS offices in the metropolitan Washington area won't be open any earlier or later than usual, officials said.

Here are the addresses for local IRS offices, which will be open 8:30 a.m. to 4:45 p.m. weekdays.

* In the District of Columbia, 1201 E St. NW.

* In Northern Virginia, Skyline Office Building, 5205 Leesburg Pike, Bailey's Crossroads.

* In suburban Maryland, Wheaton Plaza Shopping Center South. In addition, the IRS office in Suitland will be open Wednesday and Friday--but not Thursday. The Suitland office is located in the Pennsilver Office Building, 5408 Silver Hill Rd., Room 204, Suitland.

The IRS does offer self-help tax assistance. The procedure is for groups of 10 to 20 taxpayers to sit down in a classroom setting in the IRS office with a tax representative who guides the class through the return, line by line.

Telephone assistance also is available--but be prepared for the phone lines to be jammed this close to the deadline. In Northern Virginia, the number to call is 557-9230. In the District of Columbia, Montgomery and Prince George's County, the IRS assistance number is 488-3100. In Baltimore, the number is 962-2590. Other parts of Maryland can call the toll-free number 1-800-424-1040.

One other tax service that may help is the Tele-Tax service, which is available for Touch-Tone telephone users. The IRS has recorded 141 messages which last three to five minutes each and offer information on such topics as charitable contributions, medical deductions and dependents. A brochure listing the topics and explaining how to use the Tele-Tax service, which operates 24 hours a day, is available from IRS offices.

Finally, if you can't meet the April 15 deadline for federal taxes, you should file for an extension, using the special IRS extension form and paying any tax you believe you will owe. The extension buys you four more months of time, but it doesn't buy you any extra time on the tax you owe.

Failure to file the tax return carries a penalty of 5 percent a month up to 25 percent on the unpaid balance. In addition, you would be subject to interest on the unpaid tax balance, which currently is running 16 percent a year.