Tax payment

[Didi66]

To reduce my tax payment, should I increase my withholding for my 401K or change my W-4?

[Critter-3]

Either or both your choice. 

[NCperson]

@Didi66 however, if you adjust your W-4, then each dollar withheld for federal will reduce what you owe on April 15th by the same dollar,

but if you contribute more to your 401(k), then each dollar contributed will only reduce what you owe on April 15th by your marginal tax rate (probabably 12 cents to 22 cents for each dollar contributed)