After resigning from my job this month I was given the details of my final salary less deduction on 4th Dec.

All seemed fine.

However, I was in informed yesterday to now expect an additional 30% increase in income tax deduction against my December (final ) salary payment

The calculation they have stated is based on the following reason:

"The reason of adjust tax because during the year had been calculated on new rate which was approve by The Thai Cabinet but The Tax Authority not announce yet. last Monday (9 December) the Prime Minister announce to dissolve the parliament so now nobody know the new tax rate will be affective or not? The Inland Revenue has advised we better recalculate by the old rate (last year rate) to avoid penalty. Hopefully you are understand on the situation"

They claim all the company employees will now have a final year end income tax deduction based to this.

Is this fact or some BS they are trying pull?

That sounds strange. My company, which plays strictly by the rules, has just told us that the withholding tax is being adjusted now. HR had calculated our tax for the year on the old rate, but has readjusted for the new rate, which means a drop of quite a lot to compensate. For the remainder of the year, that is. Hope that makes sense.

That sounds strange. My company, which plays strictly by the rules, has just told us that the withholding tax is being adjusted now. HR had calculated our tax for the year on the old rate, but has readjusted for the new rate, which means a drop of quite a lot to compensate. For the remainder of the year, that is. Hope that makes sense.

Not 100% clear sorry.

What i understand is that my company has used the new rate throughout the year, but now due to circumstances they need to back calculate for the year using the old rate.

So basically deduct extra income against the Jan-Nov contributions already made, and go with the old rate only for Dec.

It's not a small sum that have suddenly deducted.

That's sounds correct.

You can see the old and proposed new rates here:

http://www.rd.go.th/publish/6045.0.html

http://www.bangkokpost.com/breakingnews/380644/

Overalll, the difference for most people will be about 5%, but what your company is doing is taking out that 5% of your total annual tax in one month. So appears to be a big hit at one time.

Either they take it out now, or you get hit for the extra tax when you submit your tax forms.

Lots of people expected the new tax rates to get rejected. It doesn't make sense that the gov't has huge expenditures (such as the rice pledging, infrastructure program, and new car program) that have cost billions upon billions of baht, and yet they thought they could lower taxes at the same time. Just ridiculous thinking in the first place.

The laws is valid, isn't it? I doubt the new government would cancel it.

The revenue director general announced on Saturday that the new tax law has been royally endorsed and is valid for the tax year 2013. Therefore the argument of OP's employer should be moot.

I read this in the paper that shall not be quoted here, by the way.

Rates of individual (personal) income tax in Thailand are to be reduced, beginning in 2013.

The rate cuts were approved 18 December 2012.

The new individual income tax rates are being expanded into eight income tax brackets (up from five brackets) by adding tax rates of 5%, 15%, and 25%. The top marginal tax rate decreases slightlyto 35% from 37%for net taxable income of THB 4 million or more (approximately U.S. $133,000).

See post #6 for additional approval.