Michael Kinsley is upset at the Authors Guild for lobbying Congress to allow its members (median income: $7,900 a year) and other authors to deduct expenses the same year they are incurred {op-ed, Aug. 27}. But he leads, ever wittily, with his chin when he quotes Kitty Kelley saying she might never have written ''The Glamor Spas'' had the present tax law been in effect when she set out to write it.

The president of the Authors Guild, Robert Massie, is on record to the effect that he would never have been able to write ''Nicholas and Alexandra'' had section 263A of the new capitalization law been in effect at the time. (His advance for that acclaimed work, incidentally, was the grand sum of $2,500.) Why, one wonders, didn't Mr. Kinsley quote him instead of Kitty Kelley? Silly! Because it would not have fit into his argument.

He writes that "the big guys are hiding behind the little guys" -- i.e., that such putative fat cats as David Halberstam, Anthony Lukas, William Shirer, Arthur Miller and William McPherson are using the specter of the proverbial starving author as a Trojan horse to procure a lascivious tax break for themselves, presumably so they can add second jacuzzis to their Southampton palazzos.

This is a distortion unworthy of Mr. Kinsley. If he doesn't approve of successful authors, that is his privilege, but it is nonetheless bad philosophy, because by denying them their jacuzzis, he is making it practically impossible for the little guy to survive. This philosophy is, of course, standard liberal operating procedure: make life wretched for the many in order to afflict the comfortable few. Mr. Kinsley is capable of better insights.

Or should the next Robert Massie just tighten his belt and write a quicker and dirtier work of history -- ''Nicholas,'' say, or maybe just ''Nick''?

CHRISTOPHER BUCKLEY

Council Member, Authors Guild

Washington