The first of seven speeches of instruction for the tabernacle covers over five chapters (Exodus 25:1-30:10). The second speech is a mere six verses (Exodus 30:11-16). It’s a simple chiasm:

A. At census, atonement (kopher) required, v. 12

B. Half shekel as contribution, v. 13

C. Everyone twenty years and older gives contribution, v. 14

B’. Half shekel as contribution, v. 15a

A’. Atonement (kaphar) money required, vv. 15b-16

The second speech seems only tangentially related to the tabernacle. It mentions the tent of meeting, but the main purpose is to give instructions for census,  typically done for military purposes (a “mustering”). Whenever Israel mustered the hosts, those who were twenty years and up (Exodus 30:14), each had to pay a half-shekel to the sanctuary (Exodus 30:16). 

What is this text doing here? One possibility is that Exodus 30:11-16 describes the funding of the tabernacle. The materials for the tabernacle come from the people, but there’s a need for continuing funding - for sacrificial animals, flour, oil, the ingredients of incense, tools, clothes, etc. Perhaps this text explains the source of the tabernacle’s maintenance. 

Certainly the census payments were one source of funding. When Israel is numbered after the exodus, there are 600,000 men above the age of 20; the census payment would have been 300,000 sanctuary shekels, presumably silver. The sanctuary shekel was somewhat heavier than the everyday shekel. The silver contribution from the congregation for the building of the sanctuary is one hundred talents and 1775 sanctuary shekels (Exodus 38:25), a bit over 260,000 shekels. In Solomon’s day, chariots went for 600 silver shekels and horses for 150 (2 Chronicles 1:17). With 300,000 shekels, you could buy 500 chariots or 2000 horses, less than Solomon purchases (2 Chronicles 1:14; 840,000 shekels on chariots) but still a sizable force. 300,000 shekels of silver is a significant quantity. 

But funding isn’t the only point of the half-shekel rule. Censuses were probably too infrequent to be the only source of funding. And we know that the supply of food for priests and sacrificial animals for the altar came from contributions of tithes and first fruits (Numbers 18; Deuteronomy 26). 

The language of Exodus 30:11-16 points in a different direction. The half-shekel is an “atonement” (kopher, the noun form, appears in v. 12; the verb, kaphar, twice in verses 15-16). This links the section to the previous section, which ends with an allusion to Yom Kippur (v. 10). It indicates the half-shekel payment is protective in some way. Taking a census is dangerous; plague might break out (v. 12), and Israel will be safe if they’ve paid their protection money. kaphar means “cover,” and the half-shekel payment screens Israel from Yahweh’s wrath.

Why would Yahweh be angry at a census? David’s experience (2 Samuel 24; 1 Chronicles 21) provides a clue. It’s an illegitimate census that provokes Yahweh’s anger, expressed as a plague. Some have suggested David angered Yahweh precisely because he failed to raise the half-shekel atonement contribution. That’s possible. It seems more likely that David provoked Yahweh by mustering Yahweh’s hosts without consulting Yahweh. David treated the armies of Israel as if they were his own armies, rather than the armies of the Lord. That’s one reason why a census may be dangerous.

Exodus 30, though, seems to hint at another source of anger. Everyone twenty years and older has to make atonement “for his soul” (vv. 12, 15, 16). That parallels the language of Leviticus 17:11, where the blood of sacrificial animals is given as atonement for the soul of the sinner. The half-shekel contribution takes the place of blood; it’s a silver atonement (cf. the parallels with the monetary payment required for the trespass offering, Leviticus 5:14-19). All that suggests the half-shekel was a pre-emptive, prophylactic atonement, designed to cover possible infractions among those who are mustered. The silver is placed in the tent as a “memorial” (Exodus 30:16), a permanent reminder that Israelite warriors are “covered.”

And that puts us in a military context. Israel makes war; Yahweh commands Israel to make war. But God never simply overlooks the shedding of human blood. Capital punishment isn’t exactly an exception: The blood of a murderer is retribution for the blood of his victim. Outside the context, all human bloodshed has to be repaid. Even in a just war, shedding blood is “wrong” and requires covering.

One last note: Verse 15 emphasizes that the half-shekel is a flat contribution, no matter how wealthy or poor the contributor. Some have suggested this provides biblical support for a “flat tax.” That doesn’t follow for a couple of reasons: First, this is not a “tax” but atonement money; second, the sanctuary was also supported by a proportionate (though not graduated) tax, the 10% tithe of produce. But the equity of the payment is notable. Israel’s army isn’t made up of the nobility; everyone is included. All are mustered, equipped, and commissioned to carry on the wars of Yahweh.