The widespread custom is to light a 24-hour candle (typically called a “yahrzeit candle” or ner neshamah, “soul candle”) in memory of our loved ones each year on the anniversary of their passing. This idea is inspired by the verse, “Man's soul is the L-rd's lamp.1” Other customs include leaving a candle burning for the duration of Shivah (the seven-day mourning period), lighting a candle for the entire first year following the passing, and lighting a candle whenever Yizkor (the memorial prayer) is said in synagogue. Additionally, many have the custom to light a yahrzeit candle for the duration of Yom Kippur for the souls of those who have passed on.

See: Why and When to Light a Yahrzeit Candle?

For the purposes of this article, we are not talking about a yahrzeit candle that was lit in order to have a preexisting flame to light with on a holiday. There is no question that there is nothing sacred about such a candle and it may be repurposed. The question is about a candle that was lit in commemoration of a departed soul. Can you use the light of a yahrzeit candle to read by, or even light another candle from its flame?

Benefiting From a Ner Neshamah (Yahrzeit Candle)

There is a debate about whether a yahrzeit candle falls under the general halachic category of a candle designated for a mitzvah,2 or whether it is even stricter and considered a candle made specifically for the departed. Jewish law generally forbids deriving personal benefit from anything made specifically for the departed.3

Using the Light

The consensus among halachic authorities is that, even if it is considered an item made specifically for the departed, you may still benefit from the light of a yahrzeit candle. The reasoning is that the prohibition applies to benefiting from the physical substance dedicated in the deceased's honor — the oil, wax and wick themselves — not to the light it casts. Since light isn't a tangible product being consumed, using it doesn't constitute forbidden benefit from the candle itself.4

Kindling Another Flame

What about lighting something else — a cigarette, another candle — directly from the yahrzeit flame? Opinions differ, with some distinguishing between candles lit in the synagogue and those lit at home.5

Practically, the Ketav Sofer sums it up simply: strictly by the letter of the law, one may even take fire from a yahrzeit candle. He adds, however, that common custom is to be stringent and avoid it. People are careful to set the candle aside and not use it directly, treating it with the same deference given to a candle lit for a mitzvah.6

Repurposing Leftover Wax or Oil

Based on the above, it seems that under both views of the yahrzeit candle, you would technically be allowed to use its light or light another candle from it.

However, what you may do with the remains after the candle burns out, gets a bit more complicated.

If we view the yahrzeit candle as having the halachik status of a candle lit for the deceased, then you may not use any leftover wax or oil for anything else. Because the candle was lit with the intent that the entire candle, every bit of wax and oil, would be consumed in honor of the deceased, anything leftover retains that forbidden status. This is likened to the halachah governing burial shrouds: once given with the intention of permanent use for the deceased, they remain forbidden for any other use.7

On the other hand, if it is viewed, as the majority seem to view it, simply as a candle lit for a mitzvah (and a candle lit in honor of the deceased is referring to a candle lit for the funeral, etc.8), then one can donate any extra oil or wax to the synagogue or use it to light a candle to learn some Torah.9

That said, it should be noted that the custom is that ideally the yahrtzeit candle is left to burn down completely, so regardless, nothing considerable would be left.10

Havdalah After Yom Kippur

The above often comes into play for Havdalah following Yom Kippur.

Ordinarily, during the post-Shabbat Havdalah, we say, "Blessed are you, L‑rd our G‑d, King of the universe, who creates the lights of fire," while holding a multi-wicked candle. This blessing is appropriate on Saturday night, as Adam created fire for the first time on Saturday night. During Havdalah said after a holiday, however, we don't recite this blessing, because fire is not relevant to the end of the holiday. The exception is the night after Yom Kippur, when we do say the blessing, since cooking and adjusting the size of a flame are forbidden on Yom Kippur (unlike the other holidays).

However, a key difference exists between the post-Yom Kippur Havdalah candle and the post-Shabbat candle. The point of the post-Shabbat candle is to commemorate how fire was created from nothing. Therefore, we can use fire that was created on Saturday night. The point of the post-Yom Kippur candle is that until now fire was forbidden, and now it is permitted. We therefore use a flame that "observed" Yom Kippur, i.e., it was lit before Yom Kippur and was not adjusted over the holiday. To have such a candle after Yom Kippur ends, ideally we light a separate 24-hour-plus candle before Yom Kippur, commonly called a yahrzeit candle.11

Using a Yahrtzeit Candle for Havdalah

If no dedicated candle was lit in advance, you can use a yahrzeit (memorial) candle that was already burning before Yom Kippur and left untouched throughout the day. As we explained, using the light of such a candle is permitted. Taking an actual flame from it — to light the Havdalah candle — is also permitted according to the letter of the law, though many are careful to avoid doing so out of respect for the candle's dedication to the deceased's memory. For the sake of a mitzvah like Havdalah, however, when needed, we rely on the lenient view and light directly from it.

Since we don’t light the yahrzeit candle for its light, but to honor the deceased, we don't use the candle itself for Havdalah.12 Instead, we light a separate, ordinary candle from the yahrzeit flame, and use that candle for Havdalah. This way, the Havdalah flame is still, in essence, fire that was alight and untouched throughout Yom Kippur, but is also lit for the purpose of its light.13

When we light the yahrtzeit candles representing the everlasting souls of the departed, we keep in mind that the soul is eternal and we will eventually be reunited with our loved ones, with the Future Redemption. May it happen speedily, in our days!