Rickety technology at the Internal Revenue Service was not the direct cause of last week’s Tax Day meltdown, in which the agency’s systems temporarily stopped accepting returns on the frantic last day to file them. But it should be a wake-up call for Congress, which for years disinvested in the agency.

To say that IRS technology is obsolete is an understatement. “Approximately 64 percent of IRS hardware is aged, and 32 percent of supporting software is two or more releases behind the industry standard, with 15 percent more than four releases behind,” IRS Deputy Commissioner Jeffrey Tribiano testified to Congress in October.

The IRS has been improving its customer service, and Congress recently allocated $320 million to help it implement Republicans’ new tax law. Last week the House also passed a bipartisan reform package that would help improve the agency’s online systems, including by allowing it to take credit card payments. But these measures do not make up for years of funding shortfalls.

Lawmakers should not feel as if their work is done. The House bill should be the starting point for improving the IRS.