Before Self Assessment the statutory due date of Class 4
liability was the same as any associated tax in the assessment and
depended on whether the assessment was made on time or late.
Assessments made on time were due on 1 January and 1 July in the
year of assessment. Late assessments were due 30 days after issue.
Example: If tax for 1993/94 was not assessed until
15 October 1997, both the tax and the Class 4 were due on 14
November 1997, and so the six year limit for limitation purposes
cannot begin to run until then.
In Self Assessment, the statutory due date for both tax and
Class 4 NICs is the 31st January following the end of the relevant
tax year.
So the due and payable date under Self Assessment is fixed in
relation to the tax year where the Self Assessment return is
submitted, including cases where an SA determination is displaced
by a self assessment.
In circumstances where the Self Assessment return is amended or corrected and the taxpayer does not dispute the matter within 30 days, the amended liability is due and payable on the later of:
The date of amendment will be recorded on the SA statement.
If the assessment (or SA amendment) is appealed and payment
postponed, any amount payable on determination of the appeal is due
30 days after issue of the notice under S55(9) of the Taxes
Management Act 1970.
A non-postponed amount is due as if there is no appeal, 30
days from the issue of the amendment under S55(2) Taxes Management
Act 1970.
Revenue determinations under Self Assessment are determinations of income tax. Class 4 NICs are not identified separately. Therefore, an enforcement action for a determination is not susceptible to a defence of limitation.
HMRC has 5 years from the filing date in which to issue a
determination. The taxpayer has 12 months from the date of issue of
the determination in which to file a return. A self assessment will
not be accepted later than six years after the filing date (S28C
(5) TMA 1970).
If a self assessment displaces a determination then the due
date for any Class 4 is the original statutory due date (S59B(4)
TMA 1970).
If proceedings have been commenced for the determination and
have not been concluded, then they can continue for the revised
amount (as if they had originally been taken for the self
assessment) (S28C (4) TMA 1970). A defence of limitation cannot
therefore apply.
If an earlier determination has been paid, and the taxpayer
then submits a return showing further debt, take proceedings for
the debt on the return within six years from the date of the last
payment.
You should respond to a defence of limitation that payment of
the determination was a payment on account of the debt, and the
limitation date is advanced accordingly under Section 29(5)
Limitation Act 1980.
SA payments on account are payments on account of income tax.
Class 4 NICs are not identified separately until the SA return is
filed.
If payments on account are not made, or are less than the
self assessment the statutory due date for the Class 4 remains the
31st January following the end of the tax year (S59B(4) Taxes
Management Act 1970).
Where a “discovery” assessment is made under SA, the
due date for both tax and Class 4 NICs is 30 days from the issue of
the notice where there is no application to postpone payment
(S59B(6) Taxes Management Act 1970) or for any non-postponed amount
(S55(2) Taxes Management Act 1970).
Any further tax or Class 4 payable following determination of
the appeal is due 30 days from the determination (S55(9) Taxes
Management Act 1970).
