Hi, Bill.
WHY do you want to show this as a CURRENT tax expense? You said it is for a prior year. It should be recorded as an expense of that year. Since that year's books have already been closed, the only correct way is to go back and open that year's accounting and make the entry there. Since that is usually not possible or practical, the next-best solution is to record the whole $1,000 as a current-year expense in a Category (in Quicken) with a name such as "Prior-year Tax". The initial entry would debit this Category $1,000 and credit the IRS Liability account $1,000. Your monthly payments then would reduce the liability, but not change the already-entered expense amount. The expense was for a prior year; this year, you are not paying an expense, you are paying off a debt.
You know, of course, that federal income taxes are not deductible, whether they are for the current year or a prior year, so this exercise is purely for your own accounting, not for your tax return. Any interest or penalties would be handled separately; those amounts are not taxes but they are expenses and liabilities until paid. When I was in practice, the interest was deductible when paid, but those years are far behind us.
Some taxes, such as state income taxes, may be deductible in the year paid, so they may require different treatment. But you did say "IRS", so I assume these are federal income taxes.
If I've misunderstood your question, please post back.
RC