The US needs to do end of year taxes like some other countries. For 90% of the population, just send them a letter with what the IRS believes the result to be, and ask if the person agrees or not.
Let's be honest, the overwhelming majority of the population owns no homes and only has a simple 1040 to file. They have no additional income from investments. The most they may have is a second job. The IRS already knows 100% of what these people owe.
What each person owes is based on what employer's report to the IRS, and what financial institutes such as banks report to the IRS. If the employee underpaid taxes, or overpaid taxes, it should be simple for the IRS to have software that can calculate all of that. Just send the employee a letter, telling them if they owe taxes or not, or if they are due a refund. And if the employee agrees, then take action accordingly, whether it is the employee writes a check, or if the IRS issues a refund. Done. Simple. Don't need to pay an accountant for any of that.
For those that disagree with the assessed taxes, they may file what they believe is the correct tax return, with corroborating documentation. At that point, whether they need an accountant or not is up to them. That's their problem. This would drastically reduce the manpower needed by the IRS to manage year-end tax returns because the majority of tax filers would already be filed and only awaiting confirmation from the individuals. This would make it vastly easier for the IRS to concentrate on those who disagree with the automated calculations and those who dodge taxes.