Today is not a national holiday. Yet it is a celebratory occasion of sorts for those who manage to get their income-tax returns filed before the midnight deadline.

Millions of Americans also are looking forward to getting tax refunds.

Then again, if you are due a refund, that just means the government has held your money for an extended period.

And if you aren’t due a refund, that means you had better pay up.

Beyond such familiar April 15 laments, however, lies this galling, annual realization:

If Washington had to collect its income-tax revenue in one big chunk on every April 15 instead of taking it out in smaller chunks from most working Americans’ salaries on a regular basis, the federal government would be even more broke than it already is.

And if Americans weren’t spending an estimated $168 billion a year on doing their taxes, they might not be as individually broke, either.

Thus, calls for “tax reform” proliferate.

Some folks want to scrap not just the income tax but the Internal — or is that the Infernal? — Revenue Service.

Our Founding Fathers were wary enough of an income tax to specifically prohibit it in the Constitution.

That ban was overturned one century ago by the 16th Amendment. South Carolina’s General Assembly was among 42 of the then-48 state legislatures that voted to approve it.

Back then, critics of that seemingly radical move warned that eventually Congress might tax as much as 10 percent of our income. If only ...

These days, competing critics tout the Flat Tax, the Fair Tax, the Value Added Tax (former Sen. Fritz Hollings’ favored option) and other alternatives to the increasingly complex and confounding income tax.

Just remember, however we’re taxed, somebody has to pay for what government insists that it can — and must — do for us.

That will remain the bottom-line case, no matter how “simple” or “fair” we make it.

Remember, too, that even with all of the money it collects from taxpayers and other sources, Washington has run up a record $16.81 trillion national debt.

And remember, at this possible tipping point, that nearly half of American adults pay no income tax — though plenty more have payroll taxes deducted for Social Security and Medicare, with matching “contributions” from their employers.

So at the risk of a Mitt Romney-like gaffe:

What stake do all of those non-income-tax-paying folks have in keeping the rates low enough to avoid stifling our supposedly free-market economy?

Finally, remember this warning that Plato issued roughly 2,400 years ago:

“When there is an income tax, the just man will pay more and the unjust less on the same amount of income.”

But regardless of that ancient, enduring wisdom, Happy Tax Day.

And many happy returns.