By MARTIN VAUGHAN

WASHINGTON — Some married couples would pay thousands of dollars more for the same health insurance coverage as unmarried people living together, under the health insurance overhaul plan pending in Congress.

The built-in “marriage penalty” in both House and Senate healthcare bills has received scant attention. But for scores of low-income and middle-income couples, it could mean a hike of $2,000 or more in annual insurance premiums the moment they say “I do.”

The disparity comes about in part because subsidies for purchasing health insurance under the plan from congressional Democrats are pegged to federal poverty guidelines. That has the effect of limiting subsidies for married couples with a combined income, compared to if the individuals are single.

People who get their health insurance through an employer wouldn’t be affected. Only people that buy subsidized insurance through new exchanges set up by the legislation stand to be impacted. About 17 million people would receive such subsidies in 2016 under the House plan, the Congressional Budget Office estimates.

The bills cap the annual amount people making less than 400% of the federal poverty level must pay for health insurance premiums, ranging from 1.5% of income for the poorest to 11% at the top end, under the House plan.

For an unmarried couple with income of $25,000 each, combined premiums would be capped at $3,076 per year, under the House bill. If the couple gets married, with a combined income of $50,000, their annual premium cap jumps to $5,160 — a “penalty” of $2,084. Those figures were included in a memo prepared by House Republican staff.

The disparity is slightly smaller in the Senate version of health-care legislation,