payment for the period of the underpayment, 
using an interest rate equal to the excess of—
‘‘(i) 175 percent of the Federal mid-
term rate (as in effect under section 1274 
for the 1st month of such plan year), over 
‘‘(ii) the effective rate of interest for 
the plan for the plan year. 
‘‘(B) AMOUNT
OF
UNDERPAYMENT, PE-
RIOD
OF
UNDERPAYMENT.—For purposes of 
subparagraph (A)—
‘‘(i) AMOUNT.—The amount of the 
underpayment shall be the excess of—
‘‘(I) the required installment, 
over 
‘‘(II) the amount (if any) of the 
installment contributed to or under 
the plan on or before the due date for 
the installment. 
‘‘(ii) PERIOD OF UNDERPAYMENT.—
The period for which any interest is 
charged under this paragraph with respect 
to any portion of the underpayment shall 
run from the due date for the installment 
to the date on which such portion is con-
tributed to or under the plan.
‘‘(iii) ORDER
OF
CREDITING
CON-
TRIBUTIONS.—For 
purposes 
of 
clause 
(i)(II), contributions shall be credited 
against unpaid required installments in the 
order in which such installments are re-
quired to be paid. 
‘‘(C) NUMBER
OF
REQUIRED
INSTALL-
MENTS; DUE
DATES.—For purposes of this 
paragraph—
‘‘(i) PAYABLE IN 4 INSTALLMENTS.—
There shall be 4 required installments for 
each plan year. 
‘‘(ii) TIME
FOR
PAYMENT
OF
IN-
STALLMENTS.—The due dates for required 
installments are set forth in the following 
table:
‘‘In the case of the following 
required installment:
The due date is: 
1st ...........................................................................
April 15
2nd .........................................................................
July 15
3rd ..........................................................................
October 15
4th ..........................................................................
January 15 of the fol-
lowing year 
‘‘(D) AMOUNT
OF
REQUIRED
INSTALL-
MENT.—For purposes of this paragraph—
‘‘(i) IN
GENERAL.—The amount of 
any required installment shall be 25 per-
cent of the required annual payment. 
‘‘(ii) REQUIRED ANNUAL PAYMENT.—
For purposes of clause (i), the term ‘re-
quired annual payment’ means the lesser 
of—
‘‘(I) 90 percent of the minimum 
required contribution (without regard 
to any waiver under section 302(c)) to 
the plan for the plan year under this 
section, or 
‘‘(II) in the case of a plan year 
beginning after 2007, 100 percent of 
the minimum required contribution 
(without regard to any waiver under 
section 302(c)) to the plan for the 
preceding plan year. 
Subclause (II) shall not apply if the pre-
ceding plan year referred to in such clause 
was not a year of 12 months. 
‘‘(E) FISCAL YEARS AND SHORT YEARS.—
‘‘(i) FISCAL YEARS.—In applying this 
paragraph to a plan year beginning on any 
date other than January 1, there shall be
substituted for the months specified in this 
paragraph, the months which correspond 
thereto. 
‘‘(ii) SHORT PLAN YEAR.—This sub-
paragraph shall be applied to plan years of 
less than 12 months in accordance with 
regulations prescribed by the Secretary of 
the Treasury. 
‘‘(4) LIQUIDITY REQUIREMENT IN CONNECTION 
WITH QUARTERLY CONTRIBUTIONS.—
‘‘(A) IN GENERAL.—A plan to which this 
paragraph applies shall be treated as failing to 
pay the full amount of any required installment 
under paragraph (3) to the extent that the 
value of the liquid assets paid in such install-
ment is less than the liquidity shortfall (wheth-
er or not such liquidity shortfall exceeds the 
amount of such installment required to be paid 
but for this paragraph). 
‘‘(B) PLANS
TO
WHICH
PARAGRAPH
AP-
PLIES.—This paragraph shall apply to a plan 
(other than a plan that would be described in 
subsection (f)(2)(B) if ‘100’ were substituted 
for ‘500’ therein) which—