This morning, amidst controversy over Donald Trump’s possible financial ties to Russia, Trump’s campaign manager Paul Manafort told CBS’ Norah O’Donnell that the Republican nominee would break from more than 40 years of tradition by not releasing his tax returns due to a current IRS audit.

Specifically, Mr. Manafort said:

“Mr. Trump has said that his taxes are under audit and he will not be releasing them. It has nothing to do with Russia, it has nothing to do with any country other than the United States and his normal tax auditing processes, so that issue will be dealt with when the audits are done.”

(Of note: The IRS has said that it is rare to be audited as often as Trump claims. The head of the IRS also noted that nothing prevents taxpayers from releasing their own information.)

The Sunlight Foundation has urged Congress to require presidential candidates to disclose their tax returns.

Why are tax returns such a big deal?

We believe tax returns, when considered in conjunction with financial disclosure forms, help paint a fuller picture of the candidate’s financial dealings. It’s a snapshot of their financial positions and interests. For more than four decades, presidential candidates have seemed to agree with our perspective, and every candidate since Carter has released tax returns voluntarily to the public.

What do we glean from these separate pieces of information?

From tax returns we learn:

• Yearly income of the candidate
• How much the candidate paid in taxes and the tax rate
• What deductions and tax credits claimed
• Real estate taxes and abatements
• Investments
• How much the candidate gave to charity (which could shed light on their values and priorities)
• To whom the candidate owes money
• Who are the candidates in business with and the financial positions of those companies (whether they have had gains or losses)
• May indicate if money is being held offshore

On the financial disclosure forms:

• Outside Income
• Gifts
• Assets/property owned
• Specific investments/trusts
• Possible conflicts of interest
• Certain transactions/agreements made with businesses and people
• Positions held at different companies outside of the government
• Liabilities

It’s also important to remember that unlike Congress, presidents are exempt from conflict-of-interest laws.

This makes disclosure of income tax returns especially important to shed light on areas of possible conflicts of interest. Yearly salaries are often reported in the news but tax returns reveal so much more about the character of the candidate. Their debts give us a broader sense of the state of their finances, and perhaps more importantly an idea to whom they could feel beholden. We learn how much (or little) they paid in taxes, and whether they utilized loopholes in tax law to avoid paying those taxes. It sheds light on whether they conducted activity that they have criticized on the campaign trail.

Learning about candidates businesses, business partners and the state of those activities can help understand how their judgment might be affected by their financial transactions and debts.

We learn their values and priorities from learning which charities they support.

There is a reason why banks use tax returns when evaluating mortgages: the forms offer a snapshot of a person’s financial position and their financial decision making processes. Financial disclosure forms simply don’t offer a complete picture. The two documents together may give voters a better sense of how a candidate makes financial decisions. Voters should be able to evaluate the information contained in these documents together before deciding who to vote for in November.