49. Do candidates have to report on their election campaign finances?

Electoral Act 1997 Section 36.
—(1) (a) The national agent of a political party, the election agent of a candidate and every person who incurs election expenses under section 31 (7) shall, within the fifty six days next following the polling day at an election, furnish to the Public Offices Commission a statement in writing of all election expenses (whether paid or not) incurred by such agent or person in relation to the election and the several matters to which such expenses relate, together with all relevant vouchers. (b) The national agent of a political party shall include in the statement of election expenses furnished by him or her under paragraph (a): (i) details of the election expenses incurred by the said agent pursuant to section 32 (1) (b) or 33 (1)(b), as may be appropriate; (ii) the name of each candidate whose candidature was authenticated by the party at that election and in respect of whom election expenses are deemed to have been incurred by the said agent under section 32 (1)(b)(ii) or 33 (1)(b)(ii), as may be appropriate, and the constituency in which each such candidate was a candidate at the election; and (iii) the amount of election expenses (if any) agreed in writing pursuant to section 32 (1)(b)(i) or 33 (1)(b)(i), as may be appropriate, between the party and each such candidate and the amount of election expenses incurred by the said agent pursuant to section 32 (1)(b)(i) or 33 (1)(b)(i), as may be appropriate, in respect of each such candidate. (c) The election agent of a candidate whose candidature was authenticated by a political party at the election shall include in the statement of election expenses furnished by him or her under paragraph (a) the amount of election expenses agreed in writing pursuant to section 32 (1)(b)(i) or 33 (1)(b)(i), as may be appropriate, between the candidate and such party.

The following must be included in the election expenses statement: details of all expenses incurred and payments made by the election agent and his/her authorised persons, including supplies of property, goods or services free or below cost which were used during the election period ;  details of authorised persons (which may include the candidate; a director of elections or the party's national agent) including the amount each authorised person was authorised to spend and the amounts actually spent; confirmation of the portion of the candidate's spending limit assigned by the candidate to his/her political party ... a copy of the written agreement between the candidate and the political party must be furnished by the election agent with his/her election expenses statement; details of any disputed claims for payment; information concerning late claims for payment (i.e., claims received more than 45 days after polling day) details of expenses incurred on goods, property or services used during the election period where the costs were met out of public funds. 
See Standards in Public Office Commission. 2020. Guidelines for the General Election to the 33rd Dáil 8 February 2020 [Candidates and Election agents], p. 36.