WASHINGTON — Jewish groups expressed dismay at some of the provisions of a tax overhaul that President Donald Trump and Republicans hope to complete by the end of this year.

The overhaul, broadly, slashes taxes and compensates for them to a degree by reducing deductions.

Congress launched hearings on the reforms this week after Rep. Paul Ryan, R-Wis., the speaker of the U.S. House of Representatives, unveiled them last week. It will be the first major overhaul of the taxation system in three decades. Its purported hallmark is simplicity: Ryan has said that a filer could send in a return on a postcard if he so chooses.

Of concern to Jewish groups are the removal of deductions, possible reductions in spending for social safety net programs, and the removal of a ban on tax exemptions for houses of worship.

In statements and memos, Jewish groups expressed concerns that the repeal of deductions could harm the sectors that rely on them. B’nai B’rith International, which advocates on behalf of the elderly, decried the elimination of deductions for medical expenses. Most of the Americans who take advantage of the deduction, which applies if one’s medical expenses exceed 10 percent of one’s income, are older than 65, the group said.

“Medical expenses that can be deducted from federal taxes include prescription drugs, insulin, glasses, hearings aids, payments to doctors, dentists and surgeons, nursing home fees and some long-term care insurance premiums,” it said in a statement released Friday. “We are very concerned about the impact eliminating this deduction could have on seniors, particularly low-income older Americans who have used this tax savings to save money on their vital medical needs.”

In a memo to its constituent Jewish federations, the Jewish Federations of North America singled out the proposed elimination of a tax credit for small businesses that build accommodations for the disabled.

“JFNA will actively oppose the repeal of this provision,” the memo said.

Also of concern to JFNA are changes likely to affect charitable giving, including a provision that doubles the “standard deduction” — the amount that filers can choose to claim if they forego itemized deductions.

“Because fewer taxpayers would itemize and benefit from the tax incentive for charitable contributions, overall giving would be expected to decrease,” the memo said.

The JFNA memo also said the umbrella body would lobby against eliminating the amendment that keeps houses of worship from opposing or endorsing candidates. Trump has vowed to kill the “Johnson Amendment,” named for Lyndon Johnson, who led its passage in the 1950s as a senator. A broad range of liberal Jewish groups want it preserved.

“JFNA will join with the overwhelming majority of charities, including religious groups, opposing this change that would weaken the fabric of this important protection from partisan politics that has enabled charities and houses of worship to remain focused on their mission,” the memo said.

B’nai B’rith, the National Council of Jewish Women and Bend the Arc in statements addressed concerns about the broader implications of the bill, saying the cuts — some estimates say they could slash revenue by as much as $1.5 trillion over the next decade — could destroy social safety net programs.

“This could seriously harm our more vulnerable populations, as increasing the deficit would provide cover for lawmakers to argue for cuts to important federal programs such as Medicare and Medicaid to make up for the shortfall,” B’nai B’rith said.

Bend the Arc alluded to corporate tax cuts and reductions in top level income taxes in the proposal, saying the plan “would exacerbate inequality, robbing vital programs for ordinary Americans to pay back millionaire campaign donors with tax cuts.”

NCJW said the plan was “severely skewed toward the rich.”