The analysis

Suggests it hasn't changed savings rates and effectively reduces taxes on the money you save and then used in retirement. Even the tax deferred stuff (based on how the employer match is taxed and that retirement income is generally lower).

They cite a Danish study showing that changing the subsidy for retirement contributions for the top bracket didn't move saving very much.

"The results of this study have been well received and broadly accepted. The weight of the evidence indicates that tax incentives do not increase total saving in a meaningful way."

Per the article, the treasury estimates it loses about 120 billion by allowing defined contribution plans, ignoring Roths (see Table 1)

It's not enough to balance even social security by itself, but if you get into a crisis where we need to right size the budget fast and social security is being cut I could see it. Touching anything that really drives the budget under current political conditions is politically toxic outside of the health system. There might be 100 billion or so a year you could get at outside of an emergency (some drug pricing stuff and maybe minor tweaks in billing). You could maybe get 100 billion in tax increases outside of an emergency. And maybe 100 billion in discretionary spending cuts. But that probably just pushes off reforming entitlements a bit longer.

Click here for link at https://crr.bc.edu/the-case-for-using-subsidies-for-retireme