Publication 510
taxmap/pubs/p510-053.htm#en_us_publink1000117340Deposits for a semimonthly period generally must be at least
95% of the net tax liability for that period unless the safe harbor rule
(discussed later) applies. Generally, you do not have to make a deposit for a
period in which you incurred no tax liability.
taxmap/pubs/p510-053.htm#en_us_publink1000117341Your net tax liability is your tax liability for the period minus
any claims on Schedule C (Form 720) for the period. You may figure your net tax
liability for a semimonthly period by dividing your net liability incurred
during the calendar month by two. If you use this method, you must use it for
all semimonthly periods in the calendar quarter.
 | Do not reduce your liability by any amounts from Form 720X. |
taxmap/pubs/p510-053.htm#en_us_publink1000117343The safe harbor rule applies separately to deposits under the
regular method and the alternative method. Persons who filed Form 720 for the
look-back quarter (the 2nd calendar quarter preceding the current quarter) are
considered to meet the semimonthly deposit requirement if the deposit for each
semimonthly period in the current quarter is at least
1/6 (16.67%) of the net tax liability reported for the look-back
quarter.
For the semimonthly period for which the additional deposit is
required, the additional deposit must be at least
11/90 (12.23%),
10/90
(11.12%) for non-EFTPS, of the net tax liability reported for the look-back
quarter. Also, the total deposit for that semimonthly period must be at least
1/6 (16.67%) of the net tax liability reported for the look-back
quarter.
taxmap/pubs/p510-053.htm#en_us_publink1000117344The safe harbor rule does not apply to:
- The 1st and 2nd quarters beginning on or after the effective
date of an increase in the rate of tax unless the deposit of taxes for each
semimonthly period in the calendar quarter is at least
1/6
(16.67%) of the tax liability you would have had for the look-back quarter if
the increased rate of tax had been in effect for that look-back quarter,
- Any quarter if liability includes any tax not in effect throughout
the look-back quarter, or
- For deposits under the alternative method, any quarter if
liability includes any tax not in effect throughout the look-back quarter and
the month preceding the look-back quarter.
taxmap/pubs/p510-053.htm#en_us_publink1000117345For the safe harbor rule to apply, you must:
- Make each deposit timely at an authorized financial institution,
and
- Pay any underpayment for the current quarter by the due date
of the return.
 | The IRS may withdraw the right to make deposits of tax using
the safe harbor rule from any person not complying with these rules. |
taxmap/pubs/p510-053.htm#en_us_publink1000117347You must modify the safe harbor rule if there has been an increase
in the rate of tax. You must figure your tax liability in the look-back quarter
as if the increased rate had been in effect. To qualify for the safe harbor
rule, your deposits cannot be less than
1/6 of the refigured tax liability.