CIS

CIS late filing penalties

Works out the late filing penalties on one monthly CIS return under Finance Act 2009 Schedule 55: £100 the day after the 19th, £200 at 2 months, then the greater of £300 and 5% of the deductions at 6 and at 12 months (5% alone for a first return). Takes the tax year and month, the filing date or none, today's date, the deductions and whether a return had been filed before. Returns each penalty with its date and whether it is charged, avoided or still to come. Does not cover deliberate withholding, interest on late payment, or appeals. The same as the GET, with the input as a JSON body.

post/api/v1/late-penalties

Request

  • Base URL: https://0sand1s.co.uk
  • URL: https://0sand1s.co.uk/api/v1/late-penalties
  • Auth: none declared

Request body

tax_yearinteger required

The tax year, by the calendar year it starts in: 2026 for 6 April 2026 to 5 April 2027

tax_monthinteger required

The tax month, 1 to 12: 1 is 6 April to 5 May, 12 is 6 March to 5 April

filed_onstring

The day the return was filed. Leave out or null if it has not been filed, YYYY-MM-DD

as_atstring required

Today's date. Penalties on a return not yet filed run to this date, YYYY-MM-DD

deductionsstring

The CIS deductions the return shows, or would show. Leave out or 0 for a nil return. Pounds, as a string like "1,200.00" or a number like 1200.

filed_beforeboolean

true if the contractor had already filed a CIS return before this one was due (the usual case). false for the first return, which has no £300 minimum

Response

The answer

toolstring required
resultobject required

The answer. Amounts are { pence, pounds } objects; dates are YYYY-MM-DD.

summarystring required

The answer in one line

see_alsostring uri required

The page on 0sand1s.co.uk that does the same sum or explains the rule

Changes

No recorded changes to this operation across all 1 revision of this API.