Abolish the Welsh Assembly Party probe over election return
The Abolish the Welsh Assembly Party did not submit a spending return for the assembly election, the Electoral Commission has said.
The matter is being considered by the watchdog in line with its "established enforcement policy".
Every party that contested at least one seat in the election is required by law to submit a campaign spending return.
The Abolish the Welsh Assembly Party said it submitted a return in time but there "may have been a clerical issue".
The party put up candidates on the regional lists, beating the Liberal Democrats in the North Wales and South Wales East regions.
It took sixth place with 44,286 votes, 4.4% of the total.
Last week, the Electoral Commission published figures showing just over £1.26m was spent by 17 parties and two non-party bodies during last year's campaign but the Abolish the Welsh Assembly Party was not included.
A spokesman for the Electoral Commission said: "The commission did not receive a spending return from Abolish the Welsh Assembly Party for the 2016 National Assembly for Wales election.
"Where a party fails to submit any return despite contesting the election, as in this instance, the commission considers the matter in line with our established enforcement policy."
Jonathan Harrington, the party's treasurer, said: "There may have been a clerical issue but all relevant figures were submitted by 27 July."