Wealthy individuals and their spouses will undoubtedly start looking at solo 401(k)s even more favorably if Republican’s add a fourth tax bracket for the wealthiest wage earners, investment advisors told Financial Advisor magazine.

Solo 401(k)s give sole proprietors and their spouses two important deductions that allow them to tax defer up to $54,000 each in a retirement savings ($60,000 each for sole proprietors age 50 and older), says John Knolle, principal of Saranap Wealth Advisors in Walnut Creek, Calif.

For an executive who does consulting on the side and uses her or his spouse to do sales for the company, that could mean an additional total annual tax deferral of $108,000 -- or $120,000 if they’re both 50 or older.

“Solo 401(k)s are a great place to do tax-deferred saving for high-income earners who are self-employed because they reduce taxable income,” says Adam Bergman, a tax partner with IRA Financial Group and president of IRA Financial Trust Company.

Without a fourth bracket, those with annual incomes above $418,400 could have seen a tax cut of nearly 5 percent from their current top rate of 39.6 percent. The fourth bracket the GOP is trial ballooning would preserve that top rate of 39.6 percent.

A good way to alleviate the tax sting? Solo 401(k) plans, which offer significant tax deferral to those operating or starting a small solo firm or mom-and-pop business. Under the 2017 solo 401(k) contribution rules, a plan participant under 50 can make a maximum annual employee deferral contribution of $18,000. That amount can be made in pretax, after-tax or Roth.  On the profit-sharing side, the business can make a 25 percent (20 percent in the case of a sole proprietorship or single-member LLC) annual profit-sharing contribution up to a combined maximum, including the employee deferral, of $54,000, an increase of $1,000 from 2016, Bergman says.

For plan participants over 50, an individual can make a maximum annual employee deferral contribution of $24,000. That amount can be made in pretax, after-tax or Roth. On the profit-sharing side, the business can make a 25 percent (20 percent in the case of a sole proprietorship or single member LLC) annual profit-sharing contribution up to a combined maximum, including the employee deferral, of $60,000, an increase of $1,000 from 2016, Bergman says.

“These are ideal for anyone who has a solo practice or side business or can start one and generate income,” Knolle says.

A solo 401(k) plan includes two deductions in the form of employee and employer profit-sharing contribution options, whereas a traditional IRA has a very low annual contribution limit and a SEP IRA has only an employer profit-sharing contribution option.

“This allows sole proprietors to have what every Fortune 500 employee would want but not be able to get, because their 401(k) limits them to $18,000 in annual contributions,” Bergman adds. “It’s a very good time to be self employed and contribution levels on solo 401(k)s are increasing every year,” he adds. Individuals under 50 will be able to max out at $55,000 in 2018 and those 50 and older can make max contributions of $61,000 next year.

Of course, investors would need to actually have independent contractor or sole proprietor income to invest in a solo 401(k) or the IRS could characterize the business as a hobby, says Knolle.

In order to qualify for a solo 401(k), a business can not have employees (other than a spouse), but can work with independent contractors, the IRS says.

While there was significant scuttlebutt over the weekend that 401(k) contributions would be capped, Trump already dismissed that notion Monday in a Tweet: “There will be NO change to your 401(k),” Trump said in a Twitter post. “This has always been a great and popular middle class tax break that works, and it stays!”

The Wall Street Journal and the New York Times reported on Friday that Republicans were considering an annual cap of about $2,400 on pre-tax contributions to 401(k) plans, roughly 13 percent of what workers under age 50 currently can contribute on a tax-deferred basis. That option appears to be off the table—for now.

The White House and congressional allies are floating a number of proposals to trim tax deductions in order to generate revenue lost as a result of their proposed tax cuts, the centerpiece of which is a sharp reduction in the corporate income tax rate.

That is because the Senate's version of the budget allows for tax reform to add only $1.5 trillion to the deficit over the next 10 years – potentially forcing lawmakers to make some difficult decisions about where and how much to trim the current tax code.

Lawmakers in the House and Senate are expected to finalize a 2018 budget in the coming days that will lay the groundwork for tax reform through reconciliation – which means they could pass tax cuts without the need for Democratic support.