Note: This column was updated at 3:40 p.m.

Children represent more than just an investment. But tax systems usually recognize that parents with kids are investing in the future.

And proposed changes in North Carolina’s income tax system would ensure that working-class and middle-class families free more money from the tax man because of that investment.

It’s attracted little attention so far in the income tax debate. But a provision in the N.C. Senate’s latest tax plan (Senate Bill 325) would provide more benefits to parents making up to $120,000 per year.

Let’s return to a recent debate about the progressive nature of North Carolina’s flat tax.

One of the state’s leading political columnists has argued that North Carolina’s income tax had been based historically on the idea that a bank president should pay taxes at a higher rate than a bank teller. He then proceeded to argue that North Carolina’s conversion in 2013 from a three-tiered progressive income tax to a flat-rate tax represented a significant deviation from that historical principle.

That argument is wrong. Large-scale increases in the standard deduction — or zero tax bracket, if you prefer — ensure that the bank president continues to pay a higher effective tax rate than the teller.

Federal data tell us an average bank teller makes about $25,000 per year, while an average bank president makes about $120,000. The president earns 4.8 times as much as the teller.

Under current state law, which includes a flat-rate tax of 5.499 percent, a standard deduction of $8,750 helps the teller reduce his income tax bill to $893.58, for an effective tax rate of 3.6 percent. Meanwhile, the bank president pays $6,117.63 (5.1 percent). The president’s tax bill is 6.8 times as large as the teller’s.

Following through on a Senate plan to boost the standard deduction even higher, to $10,000, would lower the respective tax bills again to $824.85 (3.3 percent) and $6,048.90 (5 percent). The president’s tax bill would be 7.3 times as large.

But that example assumes that both the teller and president are single filers. Treat them as the sole earner in a married household, and the differences become even more pronounced.

The teller’s tax bill would drop to $412.42 (1.6 percent) with the current standard deduction and $274.95 (less than 1.1 percent) under S.B. 325. In contrast, the bank president’s bill would drop to $5,636.47 (4.7 percent) under current law and $5,499 (4.6 percent) under the Senate plan. The president’s tax bill would be 13 to 20 times as large as the teller’s. Remember, this tax bill disparity is based on an income disparity of 4.8.

It’s not possible to argue with a straight face that such a system fails to ensure that the bank president pays more income tax than the bank teller.

Now let’s resume discussion of the tax treatment of children. Current state law allows taxpayers to take a credit for each dependent child, but only in households falling below a certain income threshold.

Single filers making more than $50,000, heads of household making more than $80,000, and married filers making more than $100,000 can take no child tax credit. The largest credit ($125) is reserved to single filers making no more than $20,000, heads of household making up to $32,000, and married filers making up to $40,000. Taxpayers with incomes between the two sets of income numbers listed above can take a credit of $100 per child.

We now add two children to the mix for our hypothetical families headed by a bank teller and bank president. The teller would be able to claim credits of $250 for two children. The president could claim no child tax credit.

With the current standard deduction, the teller’s state income tax bill would drop to $162.42 (0.6 percent). The bank president’s income tax bill is now nearly 35 times as large as the teller’s. Follow the Senate plan, and the teller’s state income tax bill drops to $24.95 (less than one-tenth of 1 percent.) The bank president’s income tax bill would be 220 times as large as the teller’s.

The Senate wants to cut the single flat tax rate again from 5.499 percent to 5.35 percent. At the same time, S.B. 325 would convert the child tax credit into a tax deduction. Benefits from that deduction would grow to encompass families with earnings of up to $119,999. Families making up to $40,000 per year could deduct $2,500 per child.

What would this mean for our hypothetical teller and president? Let’s consider each change separately.

First, let’s apply the lower rate. The teller’s tax bill would drop to $267.50, with the child tax credit dropping that bill down to $17.50 (.07 percent). The bank president’s bill would drop to $5,350 (4.4 percent). The president’s bill would be 305 times as large as the teller’s.

With the proposed change from a child tax credit to a child tax deduction, the teller would face zero state tax liability. The standard deduction and child tax deductions together would wipe out the teller’s income tax liability completely. Any state income tax that has been withheld during the course of the year would be refunded completely.

Once again, our bank president would reap no rewards from this change since his income falls just outside the range for child tax deductions. Still, his income tax bill would drop by $286 thanks to the lower tax rate and increased standard deduction.

Critics can argue that this scenario ignores other tax credits and deductions. They can remind me that this discussion says nothing about the sales tax. They can argue that lower-income taxpayers still might face an overall tax burden that takes a larger chunk of their wealth.

Valid or not, those arguments can be addressed elsewhere. What remains indisputable is that the two primary changes in North Carolina’s income tax since 2013 — a lower, flatter rate combined with a higher standard deduction — continue North Carolina’s long tradition of targeting higher-income earners to pay a larger share of that income in taxes.

The Senate’s proposed change in tax treatment of children follows that tradition as well.

Mitch Kokai is senior political analyst for the John Locke Foundation.