Q In your column of Feb. 17, I didn't understand the item dealing with the "long-term municipal bond" and the company that "went bankrupt." Did you mean the brokerage? I don't know of any municipal "companies." In the interest of not over-scaring municipal bond holders, how about a clarification? A I guess a clarification is needed, because other readers wrote on the same question.

I always try to write for you people out there who read this column, but sometimes I slip up. With a clear picture in my mind of what a writer is talking about, I forget that the picture may not be as clear to everyone else, and I fail to explain some necessary background.

With that apology, let me clarify what we're talking about here. For a while, municipalities were authorized to cosponsor municipal bonds with a private corporation for certain industrial purposes. Quite a few of these bonds were issued for such purposes as financing facilities to reduce pollution from an industrial plant.

Perhaps pollution-control equipment was required for the plant to continue operating. The host municipality would put its name on the bonds to qualify them for tax exemption, thus getting the company a lower interest rate. Meanwhile, the city saved some jobs for its residents and kept a piece of valuable property on its tax rolls.

Industrial revenue bonds, as they are called, were used for other purposes, such as financing construction of a sports arena, a convention or trade show center (to be operated by a nongovernmental agency) or a building as part of a package to induce a company to locate a new plant within the municipal boundaries.

Payment of interest and principal was not assured by the municipality, as in the case of the housing authority bonds that caused concern for at least one reader, but rather by the sponsoring industrial corporation -- which could go bankrupt, resulting in the loss of the package.

I hope this clears up the confusion created by my failure to explain the circumstances in the original column. Incidentally, as of the beginning of this year, some restrictions were imposed on industrial revenue bonds that are expected to curtail new issues severely but do not affect the tax status of earlier industrial revenue bonds. Q I wish to bring to your attention that your column of June 3, 1985, is not correct regarding the Keogh reporting of a single self-employed person. I filed IRS Form 5500-C last year, so I can file the shorter 5500-R for the next two years. In your column, you said you can do the form in 30 minutes. But when you file 5500-R you must also file several more at the same time, and they're giving me a lot of trouble. A I hope you're not still fighting with those other forms (which I have omitted from your question because I'll mention them here in the answer). The first thing you note is that the instructions for Form 5500-R (which you included with your letter) ask you to include the supplementary forms only "if they are required to be filed."

As to the three specified forms: Schedule SSA (Form 5500) is only required if one or more plan participants was separated from service with deferred vested benefits, and no benefits were paid to that participant during the year -- not applicable to a sole proprietor without employes.

Schedule A (Form 5500) is required to report insurance information if insurance is a part of a retirement plan. You said your account was with a mutual fund organization, so throw Schedule A away.

Finally, Schedule B contains actuarial information for a defined benefit plan subject to the minimum funding standards of the IRS code. Because your plan, like most single-person Keoghs, is probably a defined contribution or profit-sharing plan rather than a defined benefit plan, you don't need this schedule either.

So now you can go back to completing just Form 5500-R, which -- as I said last June -- shouldn't take more than about 30 minutes. Incidentally, for all you Keogh people out there, Form 5500-R for 1985 is due at the IRS not later than July 31, 1986. (Form 5500-C is required if this is either an initial or final report or if you hadn't filed the longer form in either of the two preceding years.)

Abramson is a family financial counselor and tax adviser. Questions of general interest on tax matters, insurance, investments, estate planning and other aspects of family finances will be answered in this column. Advice cannot be given on an individual basis. Address all questions to E. M. Abramson, The Washington Post, Business News, 1150 15th St. NW, Washington, D.C. 20071.