Post-Tax Deducations: A Complete Guide

Different kinds of deductions are held from employees’ paychecks. Contributions to the pension plan, social insurance coverage, federal, state, and local taxes are just several examples of various payments that must be fulfilled regularly. Nevertheless, there is sometimes an option between a pre-tax and a post-tax deduction. Thus, the definition of post-tax deductions embraces voluntary and mandatory payments deducted from gross pay. 

Pre-tax deductions are subtracted from the paycheck and go towards Traditional 401 (k) retirement contributions, health insurance, or other removals. In other words, to calculate pre-tax deductions, one has to do the deductions first and then hold the taxes from the remaining amount. 

But with the post-tax deduction, it works the other way around. Initially, the statutory taxes have to be paid from the whole amount, and only then, other deductions must be subtracted. For example, two employees have the same monthly salary of $4000 and deductions of $500. Following the pre-tax type of deductions, the first employee will pay taxes from $3500 ($4000-$500), while the second person opting for post-tax deductions has to pay taxes from $4000. As a rule, pre-tax deductions are more beneficial for a person as the taxable income is lower and it has more monetary benefits.

To have proper understanding of post-tax deduction is crucial both for an employer and an employed specialist, because it can help with financial planning and influence taxable income. For instance, the size of the payroll influences the eligibility for income-based aid like medical or childcare support programs. Also, post tax deductions and lower net income play a role in eligibility for loans and mortgages. 

Common types of post-tax deductions

1. Wage garnishments. The court-ordered payments that must be paid by an employer. Student loans, child alimony, and penalties that a taxpayer had not paid before. Having wage garnishments is not supposed to be a reason for dismissal, and not more than a quarter of the taxpayer’s take-home pay must be handled for covering the payments. 
2. Life and disability insurance premiums. Some companies practise pre-post payroll deductions in terms of insurances, while others do it differently. The choice of the plan depends on tax legislation and state possibilities.
3. Membership fees. Being a member of an association or union requires the payment of monthly fees. Popular entities are the AMA (American Medical Association), NEA (National Educational Association), International Real Estate Federation. Monthly fees range from $20 to $5. 
4. Charitable contributions. Whether it is voluntary support of non-commercial organizations or charitable foundations, the fees are usually made after the taxes are held.
5. Roth 401(k) contributions. Deductions that are made according to the pension plan are called 401(k) contributions. The traditional form of them is paid before taxes are applied, while the Roth 401(k) is subject to an after tax deduction. Roth 401(k) is more suitable for those who intend to have greater pension income in the future and do not bother themselves with paying taxes later. 
6. Personal savings accounts. Deductions to direct bank deposits, non-retirement plans, or other investment tools. 
7. Additional employee deductions. Payments for the usage of parking lots, commuting, uniform or canteen expenses, and college saving plans are a few examples of these possible financial subtractions.

Legal considerations of post-tax deduction

Financial operations are normally done by payroll specialists. An accountant, an outsourced payroll provider, or a business owner has to subtract the feasible payments and pay the net income to their employees. Even minor mistakes may lead to dire consequences. So, it is fundamental to follow the next recommendations:

• Have an explicit written consent from an employee. To avoid unexpectedly low net pay by an employer, it is better to have an authorized permission on future deductions. It may be a surprise for a specialist to find out the price of the union fee or the expenses of a new uniform.
• Have a clear breakdown of federal and state laws. To know the FLSA (Fair Labor Standards Act) is necessary since the minimum wage is defined by this document. And various before- and after-tax deductions may influence the amount received by an employer. For example, the minimum wage in the USA is $7,25 per hour, and if an employer obtains less after post-tax deductions, it is a violation of the labor law. The same is true for charging more than the defined amount for medical insurance. 
• Be aware of the consequences of unauthorized post-tax deductions. The recruiter can only charge the fees that have been discussed and agreed between both sides meaning that no hidden fees must be applied. Otherwise, the employer may go to the Department of Labor or appeal to the court. Payments for new uniforms or for a broken working computer must be negotiated first or proved, otherwise, it might be illegal.
• Post-tax deductions do not impact the taxable income. So, it does not lower the tax burden, but it can have other benefits.

Pre-tax versus post-tax: the main differences

• Net pay influence. The higher the amount in the payroll is, the higher the taxes should be paid. Thus, pre-tax deductions decrease the final amount of the taxable income. 
• Owe tax payments in the future. Pre-tax deduction is supposed to be the one that requires the user to pay taxes later. It applies to the regular tax withholding during payroll and also the specifics of the traditional 401(k) usage. To explain, when a person opts to do traditional pension financing, later, the withdrawal of pension savings will be a subject of taxation.
• HSA and FSA contributions are paid before taxation. Fees for medical expenses are not taxed. It means that an employee can cover medical expenses first and then pay the taxes from the rest of the payroll. Choosing FSA or HSA means that up to $4,300 in 2025 can be deferred annually from the pre-tax payroll for future spending related to healthcare. If the amount is not used, it will be burned by the end of the year. This method is quite common for those who tend to save up money on medical expenses. 
• Transportation perks. It is allowed to pay for the usage of carpool or public transport, such as the subway, buses or trains before taxation. The payment for car parking can be also held pre-tax. The limit for commuting in 2025 constitutes 325$ according to the Internal Revenue Service (IRS).

How to calculate after-tax deductions?

1. No matter if the payroll is done by an HR specialist, an accountant, or a business owner, first, it is crucial to find out the amount of gross pay for each employee. Take into account the prior period worked and the hour rates. Consider overworked time, penalties and sick leaves as well.
2. Conduct pre-tax deductions if applicable.
3. Define the payroll taxes and pay to the IRS. 
4. Determine post-tax deductions. Consider retirement plans, life and disability insurance, wage garnishments, and membership fees. Have a written consent for these actions by hand.
5. Complete the pay stubs with relevant information on deductions and the adjusted income. 
6. Transfer the payroll to the employee and provide the related statement on accounting. 

A short case study of after-tax deductions

We will do a thorough review of pre-tax and after-tax deductions and trace the way how gross pay is changed into net pay.

Step 1. The gross pay for Elizabeth, who works as a real estate manager, is $4000 per month. Since she has monthly payments, the result will be relevant for each month. 

Step 2. Elizabeth’s pre-tax deductions include:

• traditional 401(k) retirement contribution – $250
• Federal Insurance Contribution Act (FICA) contributions of 6,2% for social security in 2025 – $248
• HSA fee for medical expenses – $200
• parking fee: 20 days multiplied by $10 – $200

Thus, total pre-tax deductions are 898$ and the remaining taxable income is 4000$-898$=3102$

Step 3. Next, we have to count the taxes. As the federal income tax is 12%, the employer must charge another $372. The adjusted remaining income is $2720

Step 4. The after-tax deductions include a student loan and the membership in the Real Estate Association with $150 and $30 monthly fees, respectively. The net income is $2720-$150-$30=$2520

Although the gross pay is $4000, meaning that the take-home pay equals only $2520, which was significantly reduced by both pre-tax and after-tax deductions. 

Statuary deductions

These types of payments are mandatory and set by the authorities. The breach or miscalculation in paying taxes can result in severe consequences for any organization. Even if an employee disagrees with paying the required percentage, the negative effect will still be applicable. In general, there are three main statutory deductions: FICA taxes, local income taxes, and federal income taxes. In some cases, state income taxes and wage garnishments like child support or consumer debts have to be deducted as well. 

If an organization cooperates with outsourced payroll companies, the taxation is usually done by them. Otherwise, payroll is being handled in-house. 

In addition, working with foreign workforce or hiring independent contractors for short-term or long-term projects implies different requirements. To explain, hiring international employees makes a recruiter follow the labor law of the other country. Moreover, the income taxes and FICA are not charged from the payroll, but the independent contractors have to do it autonomously in their own countries.

FICA

The FICA taxes, which have been set since 1990, are only charged from earned income, not including the other sources of dividends. The established percentage in 2025 constitutes 6,2% that is paid by an employer and another 6,2% which are paid by an employee. A similar tax is charged on self-employed people and is called the SECA tax. Once the income exceeds the limit of two hundred thousand dollars, then another 0,9% is charged from the payroll till the end of the year.The accumulated funds are allocated to provide medical care and monetary support for those who are in need or for people with disabilities. Some categories of people are exempt from paying FICA taxes. For example, students who work part-time at the same university or some emergency workers are free from paying the 6,2% tax. 

Federal income taxes

Income taxes are spread all over the world. Not all countries require their residents to pay income taxes, but most of them do. For instance, Saudi Arabia, Qatar, and Monaco do not practise personal income tax. The average proportion of the income diverted to the tax authority entities varies from 10 percent to 50 percent of the income. The highest income taxes are observed in European countries, Canada, and Australia. The contributions cover municipal needs, the army, and infrastructure maintenance as a rule. The public entities may have either a residential or a territorial system of income taxation. According to the residential system, each person employed in the country has to pay income tax from their paychecks. On the contrary, territorial law makes the passport holders pay taxes whenever they live in the country of origin, meaning that double taxation is still an issue for some experts who work in a foreign country. 

Local income taxes

Additionally to the national tax, there are local taxes that can be added to the taxable income. City taxes, state taxes, or county taxes are often charged in the USA. For instance, the most expensive city to work in 2025 is New York, where employees pay an additional 3,8% for just going to work. Nevertheless, not all the cities oblige the employees to pay extra. Florida, Alaska, and Nevada have no local income tax.

Common mistakes made during post-tax deductions

• To believe that pre-tax is always more advantageous than post-tax. The result of choosing pre-tax deductions over post-tax is the reduction of taxable income. If the annual income is low, then it can lead to eligibility for social support programs. 
• Overconsumption. Some post-tax contributions may be unnecessary or irrelevant. Regular checkups of the pay stubs may save a considerable sum of money. Memberships, canteen expenses, recurrent fees to charitable organizations, insurance premiums, or enhanced parking facilities are not always essential to pay for. 
• Overcharging. Employees must not pay for the damage that was not caused by their fault. However, some employers may try to charge money for shoplifting from a cashier or the breaking door in the office. If these charges are not supported with the evidence, it is illegal to do so.
• Inaccurate recording. If payroll is done manually, there is a risk of mistakes that may occur. Miscalculations, double taxation, and irrelevant data are the typical faults during payroll.

Post-Tax Deducations FAQ

Are post-tax deductions shown on W-2?

• Yes, but not all of them. The definition of W-2 report includes the taxes that an employer charged a year before from the employees. It also shows the amount of social security and medical taxes that were withheld by an employer and paid to the IRS. But the voluntary post-tax contributions for charity or union fees, for example, are not reflected in the report. Additionally, insurance premiums are not visible in W-2 forms, but you can find them in regular paychecks.

Can an employee choose to pay pre-tax or post-tax?

• Yes and no. Some compulsory deductions like FICA or wage garnishments are set to be pre- and post-taxed, but there is still an option for how employees might pay for their retirement plan. If a specialist intends to have short-term benefits, then traditional pre-tax payment is the best choice. On the other hand, to have lifelong tax advantages requires choosing the Roth 401(k) type of payments. 

Who pays the pre-tax deductions?

• Every financial operation is performed by an accountant, HR specialist, or an outsourced payroll provider. Nevertheless, an employee provides prior authorization to carry out the contributions. 

What is FICA?

• Federal Insurance Contribution Act. The definition is commonly used for the description of the federal payroll tax. It is a compulsory tax that funds retirement and medicare programs. The standard rate is 15,3% and is paid equally by two sides: employers and employees.

Is it possible to refuse to pay post-tax deductions?

• It depends on the kind of deductions. The voluntary deductions are not mandatory, and they are about beneficial incentives. Fees to the office gym, expenses to a new uniform, or educational courses offered by an employer are examples of post-tax deductions one is free to choose or refuse. However, if the deductions are prescribed by law, like loans or unpaid taxes, it is impossible to deny paying. Moreover, they are charged by employers without permission. 

Conclusion

Even though post-tax deductions are done by employers, it is the responsibility of employees to be aware of possible deductions and taxation. Financial management starts with a clear understanding of the difference between gross pay and net pay and the method of influence. Voluntary and involuntary post-tax deductions is one of the tools to receive more benefits from work.