I just saw someone discussing tax planning and suddenly remembered a point that many people overlook—the value of above the line deductions is actually severely underestimated.

Most people only know about the standard deduction or itemized deductions when filing taxes, but few truly understand why above the line deductions are so critical. Simply put, above the line deductions are items that can be deducted before calculating Adjusted Gross Income (AGI), which means they directly lower your AGI base. It may sound trivial, but this is actually a hidden tax optimization tool.

Why is this so important? Because many other tax benefits are based on your AGI to set thresholds. For example, medical expense deductions require you to exceed 7.5% of your AGI to qualify. If your total income is $100k, 7.5% is $7,500. Suppose you have $7,500 in medical expenses; without above the line deductions, you can't deduct a penny. But if you can lower your AGI by $20k through above the line deductions, reducing it to $80k, then the threshold drops to $6,000, and you can deduct $1,500 in medical expenses. That’s leverage.

What are included in above the line deductions? Educators’ classroom supplies (up to $250), self-employed health insurance premiums, traditional IRA contributions, student loan interest (up to $2,500), deductible part of self-employment taxes, moving expenses, HSA contributions, and more. Starting in 2020, some charitable donations can also be claimed as above the line deductions—up to $300 for singles and $600 for married filing jointly—but this only applies to cash donations.

In comparison, below the line deductions are the standard deduction or itemized deductions. About 90% of people choose the standard deduction because it’s simpler. But if your itemized deductions add up to more than the standard deduction, it’s worth itemizing—such as medical expenses, mortgage interest (on loans up to $750k), state and local taxes (up to $10k), charitable donations, etc.

The key is to understand how these two types of deductions work together. Above the line deductions lower your gross income first, then you consider below the line deductions and their thresholds. So if your situation is complex, it’s really worth taking the time to identify your above the line deduction opportunities or consulting a tax professional. Many people end up paying more tax simply because they don’t fully utilize these tools.