(Bloomberg) — Americans gave less money to charities last year partly because the Republican tax law changes made many people ineligible for tax breaks that can inspire donations.

Giving by individuals fell an estimated 3.4%, after adjusting for inflation, last year, according to a report released Tuesday by Giving USA. The numbers reflect the first year of the 2017 tax overhaul that expanded the standard deduction, a simpler way of filing taxes, but also excluded millions of taxpayers from claiming a tax break for donating to charity.

Total estimated giving, by corporations, foundations, as well as individuals, fell about 1.7%, after inflation, to $427.7 billion. Individuals account for more than two-thirds of all charitable giving. Increases in donations from corporations and foundations helped offset some of the losses from individuals.

“The environment for giving in 2018 was far more complex than most years, with shifts in tax policy and the volatility of the stock market,” Rick Dunham, chair of Giving USA Foundation, said in a press release. The report is based on data provided by donors, fund-raisers and non-profits.

The 2017 tax law nearly doubled the standard deduction to $24,000 for a couple. That change meant it was more advantageous for millions of taxpayers to file using the lump sum deduction, rather than tallying up all their tax breaks from mortgage interest payments, state and local taxes and charitable gifts.

Only about 18 million taxpayers itemized in 2018 down from 46.5 million the year before, according to estimates from the nonpartisan Joint Committee on Taxation. About 88% of filers last year took the standard deduction, which means they couldn’t write off their donations.

Religious congregations are likely to be among the most affected by the decline of individual contributions because most of their donors are also members of the church, synagogue or mosque. Congregations also don’t receive donations from corporations or foundations, Una Osili, an associate associate dean at the Lilly Family School of Philanthropy at Indiana University, said in a call with reporters.

Some nonprofits predicted that contributions could decrease substantially following the tax law changes, but the most recent data don’t show the most dire estimates coming to fruition.

Republicans and Democrats have both contemplated making the charitable contribution deduction an “above the line” tax break, meaning that taxpayers can claim it regardless of whether they itemize or not. Such a change, however, is unlikely to pass in the near future. That change could cost as much as $515 billion over a decade, according to estimates from the Tax Foundation.

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