The Pennsylvania 401(k) Trap
Pennsylvania taxes your deferrals going in. Nowhere else does. It changes how much a 401(k) is worth to you today.
Pennsylvania taxes your traditional 401(k) deferrals going in. Your W-2 box 16 will be larger than box 1, and no other state does this.
Everywhere else, a traditional 401(k) reduces your state taxable wages along with your federal ones. In Pennsylvania it does not: the state's own employer guide says elective deferrals made by salary reduction are taxable to the employee and belong in Pennsylvania gross wages.
What it costs
| State | State taxable wages | State tax | Take-home |
|---|---|---|---|
| Pennsylvania | $150,000 | $4,605 | $93,881 |
| New Jersey | $130,000 | $6,710 | $91,061 |
| New York | $130,000 | $6,956 | $91,192 |
| Ohio | $130,000 | $3,626 | $94,965 |
Why it is not as bad as it sounds
Pennsylvania then generally exempts qualified retirement income after 59 and a half. So it is a timing difference rather than double taxation: you pay Pennsylvania tax on the way in instead of on the way out.
The practical consequence is still real, though. A 401(k) buys you less immediate take-home in Pennsylvania than anywhere else, at 3.07 per cent of whatever you defer. On $20,000 that is about $614.00 a year.
What still works
Section 125 benefits — health, dental, vision and disability premiums through a cafeteria plan — are still excluded in Pennsylvania. So is your employer's matching contribution. 403(b) and 457 deferrals, however, are taxed going in exactly like a 401(k).
The numbers this sits on
| State | Federal | FICA | State | Premiums | Take-home | Effective rate |
|---|---|---|---|---|---|---|
| Texas | $17,570 | $9,180 | $0 | $0 | $93,250 | 22.3% |
| Florida | $17,570 | $9,180 | $0 | $0 | $93,250 | 22.3% |
| Washington | $17,570 | $9,180 | $0 | $1,665 | $91,585 | 23.7% |
| North Carolina | $17,570 | $9,180 | $4,387 | $0 | $88,863 | 25.9% |
| Colorado | $17,570 | $9,180 | $5,038 | $528 | $87,684 | 26.9% |
| New York | $17,570 | $9,180 | $6,203 | $443 | $86,604 | 27.8% |
| California | $17,570 | $9,180 | $7,606 | $1,560 | $84,084 | 29.9% |
| Oregon | $17,570 | $9,180 | $8,920 | $840 | $83,490 | 30.4% |
Federal withholding is identical in every row, because it is federal. Everything else moves, and the spread between the best and worst row on $120,000 is $9,760 a year. That is real money and it is still usually smaller than the rent difference between the same two places.
Two rules worth carrying away
Your bracket is not your tax rate. The bracket tells you what the next dollar costs; your average across the year is usually about ten points lower. Use the marginal rate for decisions and the effective rate for understanding what you paid.
A Section 125 benefit beats an equal 401(k) contribution on take-home. Section 125 escapes Social Security and Medicare as well as income tax; a traditional 401(k) escapes income tax only. That is 7.65 cents in the dollar, every dollar, and it is the reason to fill a health or dependent care election before adding to the 401(k) beyond the employer match.
Three states break from the federal rules on top of that: Pennsylvania taxes 401(k) deferrals going in, and California and New Jersey do not recognise HSA contributions. If you are in one of those, the arithmetic above shifts and the relevant state page says how.
Work it out
Figures on this page are for the 2026/27 tax year (6 April 2026 to 5 April 2027) and were last checked on 29 August 2026. Every rate we use is listed on the sources page.