I think one of the best ways to make a long-term passive income is by investing in FTSE 100 stocks. The UK’s premier share index is packed with companies whose proven business models and cash-rich balance sheets make them brilliant stocks to buy. Stock investing can be a bumpy ride at times. As we saw during the Covid-19 crisis, even the most reliable and financially robust company can slash or cancel dividends, as well as slump in value. However, history also shows us that a carefully created and well-diversified portfolio of shares can — over the long-term — deliver significant passive income streams. Let’s say that I’m at the beginning of my investing journey. I have a decent £9,000 ready to invest in FTSE 100 shares, and plan to spend a few hundred pounds extra each month to boost my retirement pot. The first thing I’d do is set up a tax-efficient Stocks and Shares ISA or a Self-Invested Personal Pension (SIPP). Unlike a general investment account, these products allow me to build wealth without the threat of income tax or capital gains tax hanging over my head. Please note that tax treatment depends on the individual circumstances of each...