Parliament's standards commissioner is investigating whether Labour leader Sir Keir Starmer broke the rules by being late in registering earnings and gifts.
MPs must declare within 28 days any interest which might be reasonably considered to influence their actions.
Sir Keir appears to have missed this deadline on several occasions, including over Arsenal FC tickets and a payment made for writing a book.
He said: "I am confident there is no problem here."
Gifts and payments received by MPs are regularly published fortnightly in the Register of Members' Financial Interests.
