(MONEY Magazine) – -- At last count, the IRS was holding some 80,000 undeliverable refunds from the past three years, worth nearly $47 million. Is yours among them? If you are missing a refund from at least a year ago, call the IRS district office where you filed and request an investigation into your check's whereabouts. If you are looking for your 1988 refund and it has been at least eight weeks since you filed, here is what to do: Use a Touch-Tone phone to call Tele-Tax, the IRS' automated refund and tax information service, at 800-554-4477. This is one IRS phone system that actually seems to work -- the computerized instructions came on promptly 10 out of the 10 times we tried it. (Rotary dialers may have to wait for a live operator.) Warning: keep careful records of what you are told, by whom and when. If the case of your missing refund begins to twist like an Agatha Christie novel, you will need documentation to appeal to a higher authority at the IRS. When you call Tele-Tax, be prepared to give the first Social Security number shown on your return, as well as your filing status and the exact amount of your anticipated refund. You will be keyed into one of 20 messages that will divulge your refund's fate, including processing delays owing to math errors, an invalid Social Security number or a postal snag. You may even find that another government agency has copped your refund to cover a past-due account. In the best of all worlds, when you punch in your Tele-Tax numbers, you will hear the good news: your check was mailed on a certain date.

If another month goes by and there still is no check, it may be lost in the mail. Report the problem to the district office where you filed or to Taxpayer Assistance at 800-424-1040. The operator -- get his or her name -- will verify whether the check has come back as ''undeliverable'' and send you a form to fill out and return so the check can be re-sent. You should get it in about six weeks. Should the IRS identify a mistake on your return, Tele-Tax will tell you which item is in error. Alas, your refund will be held up for at least six more weeks. You will receive a letter around the same time explaining why the amount is different from what you had expected. If you disagree, fight it by calling Taxpayer Assistance or the district IRS office where you filed. If, after repeated phone calls and correspondence, you still don't have a check, call the problem resolution officer at the district office where you filed. Now is when your documentation pays off: the problem resolution officer will usually become involved only if you can make a case that the delay is rooted in IRS procedures and not caused by the post office or your own filing mistakes.

BOX: FACT OF THE MONTH

If tax rates for individuals were raised from 15% to 16%, from 28% to 30%, and from 33% to 35%, and corporate rates were boosted from 34% to 35%, the changes would increase tax revenues as follows:

In 1990 $18.6 billion 1991 $35.2 billion 1992 $38.2 billion 1993 $41.5 billion 1994 $44.8 billion

Total by 1994 $178.3 billion Source: Congressional Budget Office