Long-term investors should always aim to bolster their passive income. By having more of it, that can make you less dependent on employment and pension income, and it can also improve your overall financial position.

A couple of high-yielding stocks to consider for your portfolio today are Cardinal Health (CAH 2.05%) and Enbridge (ENB -0.82%). Not only are their dividend payments well above the S&P 500 average of 1.4%, but their underlying businesses look sound.

A family adding coins to a piggy bank.

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1. Cardinal Health

Cardinal Health is a Dividend Aristocrat that has been raising its payouts for decades. Earlier this month, it announced another increase to its quarterly dividend. At $0.4957, it's a nominal 1% increase over the $0.4908 that the company was previously paying. It's not a huge rate hike, but over five years the company has raised its payouts by more than 7%.

With the increase in the payout, investors today would be collecting a 3.6% dividend yield. On a $25,000 investment, that could mean $900 in annual dividend income from Cardinal Health. While that's not a boatload of money, it can help complement and diversify your passive income if you're already collecting dividends from other stocks.

One of the benefits of investing in Cardinal Health is that it can make for a relatively stable and safe investment; year-to-date its shares are up 10% while the S&P 500 has fallen more than 15%. The healthcare company could be a big benefactor from a return to normal in the economy as physicians issue more prescriptions to patients. And there's already a sign that the healthcare company is on the right track. 

Sales of $44.8 billion rose 14% year-over-year for the first three months of 2022, with its pharmaceutical segment (which is its largest business unit) behind the growth, rising by 17%. Its medical segment declined by 7%.

Cardinal Health plays an important role in the industry in distributing pharmaceutical and medical products, and that can make it an extremely safe dividend stock to hang onto for years.

2. Enbridge

Pipeline stock Enbridge has performed even better than Cardinal Health this year with its shares up around 15%. It has benefited from a strong oil and gas industry and more bullishness around the sector in general with oil prices at highs not seen in years

However, even amid low oil prices, Enbridge was a relatively safe dividend stock to hold. It has long-term contracts in place that provide it with stability. Those have allowed the company to raise its dividend for the past 27 years, even as fluctuations in the price of oil created instability for other businesses in the industry. And its rate hikes have been generous, with the company averaging a compound annual dividend growth rate of 10% over that time frame.

Its dividend yield is at 6% today, which means if you invested $25,000 in this stock, you could collect $1,500 in recurring income each year. And that amount is likely to increase over time given the company's propensity to hike its payouts. 

Enbridge's earnings have been steady with the company reporting a profit of CA$1.9 billion for the first three months of 2022 -- nearly unchanged from the prior-year period. On a per-share basis, that comes out to CA$09.5 vs. the CA$0.94 that it reported a year ago. The company also reaffirmed its guidance this year, which calls for discounted cash flow per share of at least CA$5.20, which is strong enough to support its dividend. On an annual basis, Enbridge pays CA$3.44 per share.

Consistently strong financials and a high dividend yield make Enbridge an underrated oil and gas stock to buy for the long haul.