Sinn Féin MPs had already begun completing the register of members' interests before a House of Commons committee ruled they must do so, a party spokesman said today.
The spokesman said the party's four MPs - Mr Gerry Adams, Mr Martin McGuinness, Mr Pat Doherty and Ms Michelle Gildernew - had this week started to supply information to the register that its MPs would be signing.
The Standards and Privileges Committee ruled yesterday that the MPs for West Belfast, Mid Ulster, West Tyrone and Fermanagh and South Tyrone must be compelled to list their interests in the register.
There had been complaints that Sinn Féin, which was granted offices in the House of Commons and allowances following a vote at the end of last year, could escape signing the register because of a loophole that did not require MPs who do not sit in the chamber to declare their interests.
But under new rules proposed yesterday, the committee agreed that all MPs should have to fill in the register within three months of their election. The rule change will be put to a vote in the House of Commons but is expected to pass.
In the North's Assembly, Mr Adams declares that he is earning as an author and confirms that he had an unpaid directorship with Féile an Phobail Ltd, which runs the annual West Belfast Festival.
A Sinn Féin spokesman said today it supported "full openness, transparency and accountability in public life".