Find the Deduction is a game with constantly shifting rules. Each year Congress changes something in the tax law, the Internal Revenue Service issues opinions, and tax courts make their rulings. If you like a challenge, learning this year's deduction options is like a game of chess. If not, it's a tedious round of hide-and-seek. But either way, it's worth knowing the rules.

Charitable donations. Do pay attention to tightened donation regulations. The IRS now requires receipts for all deductible donations. Starting this year, all charitable deductions, no matter how small, must be substantiated either by a canceled check; bank record containing the charity name, donation amount, and date; or detailed receipt from the charity. Otherwise the contribution is not deductible.

Do start collecting your charitable acknowledgements, receipts, and cancelled checks in one place now. If you make cash donations, you'll need either a bank statement or a written communication from the charity noting the charity name, your donation amount and the date. For more, check IRS Publication 526, Charitable Contributions, on the IRS Web site, www.irs.gov.

Don't itemize donations of furniture, clothing, and other household goods that weren't in at least good condition when you gave them. While the IRS rule, instituted last year, aims to weed out junk donations, taxpayers may claim a deduction of more than $500 for any single item in any condition as long as a qualified appraisal is included with their return.

Don't deduct gas mileage used for activities and service related to Hurricane Katrina aid at a higher rate. The IRS provision allowing filers to deduct such mileage at an increased rate has expired.

Medical expenses. Do deduct premiums for the Medicare Part D prescription drug insurance program, as well as other health-insurance premiums you pay yourself. The premiums for long-term-care insurance are deductible on a sliding scale according to your age.

Do deduct gas mileage expenses for your car when used for medical reasons. The 2007 rate for such deductions is 20 cents per mile.

Do read the IRS list of deductible medical expenses (see Publication 502 under More Forms and Publications at www.irs.gov). The following costs, for example, are deductible to the extent they address a health issue: wigs recommended by a doctor for mental health of a patient suffering hair loss due to disease; special mattresses and bed boards; back supports; elastic hosiery; childbirth classes, and remedial reading instruction for dyslexic children.

Don't expect much. You can only deduct unreimbursed medical and dental expenses that exceed 7.5 percent of your adjusted gross income. If you are subject to the Alternative Minimum Tax, the floor is higher: 10 percent. (If you're self-employed, your health-insurance premiums may be 100 percent deductible. See Publication 502 for eligibility criteria.)

Retirement accounts. Do contribute to an IRA if you're eligible. Taxpayers under age 50 can put in up to $4,000; those 50 and over can sock away $5,000. Next year those amounts rise to $5,000 and $6,000 respectively. For 2007, if you're covered by a retirement plan at work, your deduction for contributions to a traditional IRA will be phased out if your AGI is more than $83,000 but less than $103,000 for joint filers. You have until the filing deadline to make a contribution.

Do fund a SEP IRA if you made money from self-employment last year. You are eligible even if you held another job and contributed to a 401(k) there.

Extended deductions. Do check the IRS Web site in late February or early March for Publication 553, which outlines popular deductions that were reinstated by Congress late last year.