Passive activity loss rules are a set of IRS provisions that limit an investor's ability to use losses generated by passive activities, such as a limited partnership interest in a real estate syndication, to offset active income like wages or business earnings. Under these rules, passive losses generally can only offset passive income, and any excess is suspended and carried forward to future years or until the investor disposes of the activity entirely. This is why a large depreciation-driven loss on a K-1 does not automatically translate into a lower tax bill on a salary.
There are notable exceptions, including a limited allowance for certain active participants in rental real estate and a broader exception for those who qualify as real estate professionals. Because the rules are technical and depend heavily on an investor's specific activities and income sources, understanding how passive loss limitations affect real estate tax efficiency is an important step before assuming any projected deduction will actually reduce a given year's taxes.
Further reading: Tax Efficient Real Estate Investing