5 Dates to Check on Anything Secondhand, and What Each Means

Some secondhand items come with a date that decides whether they are worth buying at all. A car seat has one, so does a smoke alarm, and so does that bargain mascara. The trouble is that most of us never look. This guide collects five of them, with the rule the government agencies attach to each and where to find the date.

When the item is old, the date is the price tag you can't see.

Each rule below comes from a page I opened for this article. Where I add my own advice, I say so.

The five dates at a glance

1. The car seat: six years, at least

Safe Kids says a secondhand car seat is acceptable only if you know its full history, it is not past its expiration date and the labels are present so you can check recalls. Expiration is set at least six years after manufacture, and the date is stamped on the seat. If the label is missing, the date and the recall status can't be confirmed, so the seat is out. The full list is in the used car seat checklist.

2. The smoke alarm: ten years from manufacture

The USFA says to replace the entire alarm every 10 years from its manufacture date, not the day you installed it. It also says to test each alarm monthly. A used smoke alarm is one I would skip, since you can't see its history. More in the smoke and CO alarm checklist.

3. The carbon monoxide detector: five years, or the maker's date

The CDC says to replace detectors according to the manufacturer's instructions, or every 5 years. It also suggests installing detectors near every sleeping area and checking the batteries when you change your clocks in spring and fall.

4. The mascara: weeks, not years

Here the date is not printed. The FDA says no U.S. law requires cosmetics to carry an expiration date, and that manufacturers usually recommend discarding mascara two to four months after purchase, since each use exposes it to bacteria and fungi. For a second-hand or discounted tube, my concern is that you can't know how old it is or how it was stored. If the date is unknown and it touches your eyes, I would leave it. We cover the rest in is discounted or secondhand makeup safe.

5. The refrigerator: fifteen years

ENERGY STAR says refrigerators over 15 years old could cost about $95 more a year to run, and that an old refrigerator uses about 20% more energy than a model that has earned the ENERGY STAR. The label inside the cabinet shows the age. Our used fridge guide shows how to run the numbers.

How to find a date quickly

My own tips:

• Take a phone flashlight. Labels are often on the back, the bottom or inside a cabinet wall.
• Photograph the label so you can look up the model number later.
• Ask the seller before you travel. Ask for a photo of the label. A seller who can't or won't send one has told you something.
• Do the sum. If the date means you must replace the item soon, add the cost of the replacement to the price you pay.

Where this applies in the DC area

If you shop around DC, Maryland and Virginia, you can often handle an item before you buy. That makes it easy to find a label. Browse Buy Now, check each listing's details and photos, and read the help page for how pickup and returns work.

The bottom line

Five items, five dates: six years for car seats, ten for smoke alarms, five for CO detectors, two to four months for mascara and fifteen for refrigerators. If the date isn't there, treat it as a no.

If someone you know is buying baby gear or kitchen items secondhand, send them this list first.